Multiple function name support, regex fixes

I've added support for multiple function names given as an array as suggested in issue #8 (e.g. `functionName: [ "__", "gettext" ]`). Additionally I've added a missing `\` from `\\w` in the JavaScript regex and added more spacing support (that is, previously neither `gettext ("foo")` nor `gettext( "foo" )` would have been recognized).

As a side note, it would be good to point out in the documentation that `functionName` is essentially a regex, so functions that have e.g. dots in them (`gettext.translate()`) should be escaped (`functionName: "gettext\\.translate"`).