update parser to use 2.6

was choking on &. syntax
improved error reporting slightly

rubyx.gemspec

@@ -13,6 +13,6 @@ Gem::Specification.new do |s|
   s.require_paths = ['lib']
   s.summary = 'RubyX is a native object vm without any c, one day possibly a ruby vm'
 
-  s.add_dependency "parser" , "~> 2.4.0"
+  s.add_dependency "parser" , "~> 2.6.0"
   s.add_dependency "rx-file" , "~> 0.3"
 end