This fixes three test failures on Windows:
* Two due to incorrect handling of : (on Windows, multiple : can
  be part of a path.)
* One due to newline differences

* Remove Python 2 compatibility

* remove 2/3 shims in pygments.util
* update setup.py metadata

* Remove unneeded object inheritance.

* Remove unneeded future imports.

Python f-strings: highlight expressions in curly braces

Fixes #1228

- The walrus operator, also known as assignment expressions, was introduced in Python 3.8
- Moves the Token.Operator matching root above Token.Punctuation so the walrus operator takes precedence
- Includes a test to make sure this behavior doesn't regress since it's sensitive to the order of expressions
- Fixes #1381

* Fix glob patterns for directives like Include.

* removing unnecessary escaping.

MIR is a human readable serialization format that's used to represent LLVM's
machine specific intermediate representation. It allows LLVM's developers to
see the state of the compilation process at various points, as well as test
individual pieces of the compiler. Our documentation for the format can be
found at https://llvm.org/docs/MIRLangRef.html.

Adding a lexer for this format will allow the LLVM documentation to contain
syntax highlighted examples of LLVM-MIR. Two lexers are included in this
change. 'llvm-mir' lexes the overall document format and delegates to 'llvm' and
'llvm-mir-body' as appropriate. 'llvm-mir-body' lexes the contents of the 'body:'
attribute and can be used directly to syntax highlight code examples without
including the document boilerplate.

Since the 'llvm-mir' lexer delegates to the 'llvm' lexer at times, this change
also adds the 'immarg' and 'willreturn' keywords to the 'llvm' lexer as these
were missing.

* Fix lexing of Idris compiler pragmas.

The regex for capturing Idris compiler pragmas did not separate the leading
percent sign from the disjunction of compiler directives correctly, which caused
issues such as "import" or "namespace" keywords to be mishighlighted, due to
confusion with the "%import" and "%name" compiler pragmas.

* Add unit test for Idris compiler directive lexing