fix(grammar) A range can contain an unescaped [ symbol.

Hywan · Hywan · commit ce7fd7b5a26b · 2018-01-22T10:49:55.000+01:00
`[\[]` is strictly equivalent to `[[]`. Both are valid.
diff --git a/Source/Grammar.pp b/Source/Grammar.pp
@@ -165,7 +165,7 @@
         ::negative_class_:: #negativeclass
       | ::class_::
     )
-    ( range() | literal() )+
+    ( <class_> | range() | literal() )+
     ::_class::
 
 #range:

Original file line number	Diff line number	Diff line change
`@@ -165,7 +165,7 @@`
`165`	`165`	`::negative_class_:: #negativeclass`
`166`	`166`	`\| ::class_::`
`167`	`167`	`)`
`168`		`- ( range() \| literal() )+`
	`168`	`+ ( <class_> \| range() \| literal() )+`
`169`	`169`	`::_class::`
`170`	`170`
`171`	`171`	`#range:`