Use a single token for identifiers

lib/liquid/lexer.rb

@@ -13,7 +13,7 @@ module Liquid
       '?'.freeze => :question,
       '-'.freeze => :dash
     }
-    IDENTIFIER = /\w+/
+    IDENTIFIER = /[\w-]+\??/
     SINGLE_STRING_LITERAL = /'[^\']*'/
     DOUBLE_STRING_LITERAL = /"[^\"]*"/
     NUMBER_LITERAL = /-?\d+(\.\d+)?/

lib/liquid/parser.rb

@@ -75,13 +75,6 @@ module Liquid
 
     def variable_signature
       str = consume(:id)
-      while consume?(:dash)
-        str << "-".freeze
-        str << consume(:id)
-      end
-      if consume?(:question)
-        str << "?".freeze
-      end
       if look(:open_square)
         str << consume
         str << expression