[features] General tweaks and fixes

* Add erl_features:configurable/0
  * Return configurable features, since these are the most interesting
  * Use erl_features:configurable/0 where approriate
* Change meaning of meta feature 'all' to configurable features
* Prevent using non configurable features
  * Change so that we can only enable/disable configurable features
  * Permanent features will be seen as both avilable and enabled
    by the macros FEATURE_AVAILABLE and FEATURE_ENABLED, but they
    will not be recorded in the BEAM file, nor will they be enabled
    in the runtime system.
* Force load erl_features module

* Documentation
  * General improvements
  * Remove mention of -compile attribute for features, since it
    (no longer) works and should not, as it just makes epp even
    more complicated than it is today

* Error handling
  * Improve error message for misplaced directive
  * Rewrite error handling to be more precise by distinguishing
    between invalid and non configurable features
  * Catch all unknown or non configurable features

* Keep order of +options to erlc

* Bugs
  * Fix bug to avoid multiple instances in chunk
  * Fix ordering bug for +options to erlc

* Tests
  * Remove lux scripts
  * Move tests to common test

4 files changed, 51 insertions, 7 deletions

diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml
index 3a01066410..b5b920cc79 100644
--- a/system/doc/reference_manual/expressions.xml
+++ b/system/doc/reference_manual/expressions.xml
@@ -1815,7 +1815,7 @@ end</pre>
       <item>Expressions that construct atoms, integer, floats, lists,
       tuples, records, binaries, and maps</item>
       <item>Expressions that update a map</item>
-      <item>The record epxressions <c>Expr#Name.Field</c> and <c>#Name.Field</c></item>
+      <item>The record expressions <c>Expr#Name.Field</c> and <c>#Name.Field</c></item>
       <item>Calls to the BIFs specified in tables <em>Type Test BIFs</em> and
       <em>Other BIFs Allowed in Guard Expressions</em></item>
       <item>Term comparisons</item>
diff --git a/system/doc/reference_manual/features.xml b/system/doc/reference_manual/features.xml
index ed254db55a..882cdd2582 100644
--- a/system/doc/reference_manual/features.xml
+++ b/system/doc/reference_manual/features.xml
@@ -142,13 +142,12 @@
       <item>The compiler option <seeerl
       marker="compiler:compile#feature-option"><c>{feature,
       &lt;feature&gt;, enable|disable}</c></seeerl> can be used either
-      as a <c>+&lt;term&gt;</c> option to <c>erlc</c>, in the options
-      argument to function in the <c>compile</c> module, or in the
-      <c>-compile(..)</c> attribute in a file.</item>
+      as a <c>+&lt;term&gt;</c> option to <c>erlc</c> or in the options
+      argument to functions in the <c>compile</c> module.</item>
       <tag>The feature directive</tag>
-      <item>Inside a prefix of a module, one can use a <seeerl
-      marker="compiler:compile#feature-directive"><c>-feature(&lt;feature&gt;,
-      enable|disable)</c></seeerl> directive.  This is the preferred
+      <item>Inside a prefix of a module, one can use a <seeguide
+      marker="macros#feature-directive"><c>-feature(&lt;feature&gt;,
+      enable|disable)</c></seeguide> directive.  This is the preferred
       method of enabling and disabling features.</item>
     </taglist>
     <p>
diff --git a/system/doc/reference_manual/macros.xml b/system/doc/reference_manual/macros.xml
index ffa5373613..e54e0e1d30 100644
--- a/system/doc/reference_manual/macros.xml
+++ b/system/doc/reference_manual/macros.xml
@@ -277,6 +277,27 @@ or
   </section>
 
   <section>
+    <title>
+      The -feature() directive
+    </title>
+    <marker id="feature-directive"/>
+
+    <p>
+      The directive <c>-feature(FeatureName, enable | disable)</c> can
+      be used to enable or disable the <seeguide
+      marker="system/reference_manual:features#features">feature</seeguide>
+      <c>FeatureName</c>.  This is the preferred way of enabling
+      (disabling) features, although it is possible to do it with
+      options to the compiler as well.
+    </p>
+    <p>
+      Note that the <c>-feature(..)</c> directive may only appear
+      before any syntax is used.  In practice this means it should
+      appear before any <c>-export(..)</c> or record definitions.
+    </p>
+  </section>
+
+  <section>
     <title>-error() and -warning() directives</title>
 
     <p>The directive <c>-error(Term)</c> causes a compilation error.</p>
diff --git a/system/doc/reference_manual/modules.xml b/system/doc/reference_manual/modules.xml
index 4de72d1b7f..b373e2506b 100644
--- a/system/doc/reference_manual/modules.xml
+++ b/system/doc/reference_manual/modules.xml
@@ -251,6 +251,30 @@ behaviour_info(callbacks) -> Callbacks.</pre>
   </section>
 
   <section>
+    <title>
+      The feature directive
+    </title>
+
+    <p>
+      While not a module attribute, but rather a directive (since it
+      might affect syntax), there is the <c>-feature(..)</c>
+      directive used for enabling and disabling <seeguide
+      marker="system/reference_manual:features#features">features</seeguide>.
+    </p>
+    <p>
+      The syntax is similar to that of an attribute, but has two
+      arguments:
+    </p>
+    <pre>
+-feature(FeatureName, enable | disable).</pre>
+    <p>
+      Note that the <seeguide
+      marker="macros#feature-directive">feature directive</seeguide>
+      can only appear in a prefix of the module.
+    </p>
+  </section>
+
+  <section>
     <title>Comments</title>
     <p>Comments can be placed anywhere in a module except within strings
       and quoted atoms. A comment begins with the character "%",