Fix the Chapel lexer's parsing of string literals
Fix the Chapel lexer's parsing of string literals

The Chapel lexer was trying to parse both the single and double quoted forms of
string literals with a single regex rule. This lead to errors on input like:

 "I'm a string literal!"

The fix was to split the rule out into a ' and " version.

dscorbett/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,pygments/pygments,pygments/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments