Use negative lookbehind when tokenizing string literals
Use negative lookbehind when tokenizing string literals

This can double the speed of tokenizing large RTF files that use \'hh
escape sequences.

steventhanna/linguist,christop/linguist,jtbandes/linguist,yyx990803/linguist,erkyrath/linguist,R4PaSs/linguist,meunierfrederic/octocatlinguist,stanhu/linguist,jtbandes/linguist,MostAwesomeDude/linguist,tschf/linguist,sebgod/linguist,pchaigno/linguist,MahmoudFayed/linguist,stanhu/linguist,mwpastore/linguist,c-lipka/linguist,sebgod/linguist,steventhanna/linguist,JJ/linguist,erkyrath/linguist,osorgin/linguist,pchaigno/linguist,R4PaSs/linguist,yyx990803/linguist,github/linguist,PsichiX/linguist,yyx990803/linguist,stanhu/linguist,MostAwesomeDude/linguist,erkyrath/linguist,JJ/linguist,erkyrath/linguist,christop/linguist,jrnold/linguist,meunierfrederic/octocatlinguist,MahmoudFayed/linguist,github/linguist,github/linguist,jrnold/linguist,stanhu/linguist,pchaigno/linguist,JJ/linguist,ppaulweber/github-linguist,github/linguist,pchaigno/linguist,tschf/linguist,yyx990803/linguist,sebgod/linguist,PsichiX/linguist,mwpastore/linguist,osorgin/linguist,ppaulweber/github-linguist,c-lipka/linguist,meunierfrederic/octocatlinguist,sebgod/linguist,JJ/linguist