refactor tokens as classes in themes
Merge pull request #95 from tiroc/master

refactor tokens as classes in themes
ruby: highlight . and :: in method calls as Punctuation
ruby: highlight ( in defexprs as Punctuation

not as Operator :\
v0.5.1
make lexers inheritable
make SassCommon a shared subclass
bugfix: use @name when prepending and appending
refactor cpp as a subclass of c
c: highlight `#if 0` as a comment
minor nit: use `yield_token` internally
Merge branch 'spike.inheritance'
Fix parse error on yaml lexer
c: add more type keywords
c: introduce expr_bol for non-label line starts
fix tokens from nested `#if 0`

and cover #ifdef and #ifndef in the nesting
use `super` in C++ keyword defs
cpp: put pseudo keywords in :statements
Implement RegexLexer::State#inspect
better error behavior for non-existing states