Add support for languages with multiple comment styles

[Trey Hunner]

Languages like PHP have multiple comment styles (// and # for single line comments). Currently the code only supports one single-line comment style and one multi-line comment style (optionally).

Two possible solutions:

1. Turn "symbol" definition into a List of symbol styles or allow a List to be specified optionally. PHP support could then be added like this:

   ".php": { "name": "php", "symbol": ["//", "#"]}
   

2. Use regular expressions for "symbol", "multistart", and "multiend". PHP support could then be added like this:

   ".php": { "name": "php", "symbol": r"//|#"}
   

[Tristram Oaten]

This would also allow both of python's very common docstring formats to be supported:

"""
3 double quotes
"""

'''
3 single quotes
'''

Currently on the first is supported, they are both equally valid.