Python: lex soft keywords

Some notes:

- This approach is not perfect, but it's rather simple and I can't
  think of an edge case.

- I did not use the `words` function to create the regex matching the
  keywords list, because it returns a capturing group (`()`) and it
  needs to be non-capturing here (because of `bygroups` usage).

- I chose to go to the 'soft-keywords-inner' state after both
  `match` and `case`, even though it's unnecessary for `match`
  (the inner state catches the `_` wildcard keyword which appears
  only after a `case`).

  This is mostly harmless and saves us from writing the 'soft-keywords'
  regex twice each for `match` and `case` with the extra inner state
  just for `case`.

  The only piece of code this will lex incorrectly is `match _:`
  (`_` will be lexed as keyword). I doubt though that pattern mathcing
  will be used like this.

2 files changed, 219 insertions, 0 deletions

diff --git a/tests/examplefiles/python/switch_case.txt b/tests/examplefiles/python/switch_case.txt
new file mode 100644
index 00000000..36c34fbd
--- /dev/null
+++ b/tests/examplefiles/python/switch_case.txt
@@ -0,0 +1,23 @@
+match command.split():
+    case ['to', direction] if direction in destination.route:
+        return 1
+    case 'foo' | 'bar':
+        return 2
+    case 'raz' as name:
+        return 3
+    case ['to', _]:
+        return 4
+    case else_bar:
+        return 5
+    case _:
+        return 6
+
+match command.split():
+    case _Direction():
+        return 1
+    case _ as default:
+        return 2
+
+case = 1
+match = 1
+match if True else bar
diff --git a/tests/examplefiles/python/switch_case.txt.output b/tests/examplefiles/python/switch_case.txt.output
new file mode 100644
index 00000000..2abf65a5
--- /dev/null
+++ b/tests/examplefiles/python/switch_case.txt.output
@@ -0,0 +1,196 @@
+'match'       Keyword
+' '           Text
+'command'     Name
+'.'           Operator
+'split'       Name
+'('           Punctuation
+')'           Punctuation
+':'           Punctuation
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+'['           Punctuation
+"'"           Literal.String.Single
+'to'          Literal.String.Single
+"'"           Literal.String.Single
+','           Punctuation
+' '           Text
+'direction'   Name
+']'           Punctuation
+' '           Text
+'if'          Keyword
+' '           Text
+'direction'   Name
+' '           Text
+'in'          Operator.Word
+' '           Text
+'destination' Name
+'.'           Operator
+'route'       Name
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'1'           Literal.Number.Integer
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+"'"           Literal.String.Single
+'foo'         Literal.String.Single
+"'"           Literal.String.Single
+' '           Text
+'|'           Operator
+' '           Text
+"'"           Literal.String.Single
+'bar'         Literal.String.Single
+"'"           Literal.String.Single
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'2'           Literal.Number.Integer
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+"'"           Literal.String.Single
+'raz'         Literal.String.Single
+"'"           Literal.String.Single
+' '           Text
+'as'          Keyword
+' '           Text
+'name'        Name
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'3'           Literal.Number.Integer
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+'['           Punctuation
+"'"           Literal.String.Single
+'to'          Literal.String.Single
+"'"           Literal.String.Single
+','           Punctuation
+' '           Text
+'_'           Keyword
+']'           Punctuation
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'4'           Literal.Number.Integer
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+'else_bar'    Name
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'5'           Literal.Number.Integer
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+'_'           Keyword
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'6'           Literal.Number.Integer
+'\n'          Text
+
+'\n'          Text
+
+'match'       Keyword
+' '           Text
+'command'     Name
+'.'           Operator
+'split'       Name
+'('           Punctuation
+')'           Punctuation
+':'           Punctuation
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+'_Direction'  Name
+'('           Punctuation
+')'           Punctuation
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'1'           Literal.Number.Integer
+'\n'          Text
+
+'    '        Text
+'case'        Keyword
+' '           Text
+'_'           Keyword
+' '           Text
+'as'          Keyword
+' '           Text
+'default'     Name
+':'           Punctuation
+'\n'          Text
+
+'        '    Text
+'return'      Keyword
+' '           Text
+'2'           Literal.Number.Integer
+'\n'          Text
+
+'\n'          Text
+
+'case'        Name
+' '           Text
+'='           Operator
+' '           Text
+'1'           Literal.Number.Integer
+'\n'          Text
+
+'match'       Name
+' '           Text
+'='           Operator
+' '           Text
+'1'           Literal.Number.Integer
+'\n'          Text
+
+'match'       Name
+' '           Text
+'if'          Keyword
+' '           Text
+'True'        Keyword.Constant
+' '           Text
+'else'        Keyword
+' '           Text
+'bar'         Name
+'\n'          Text