replaced spirit parser for Jones symbols by regex

I could finally find a way to parse Jones symbol using regex. Choosing between the syntactic uglyness of a boost::spirit parser and a std::regex parser is a matter of debate but it allows to get rid one more boost::spirit dependency. The parser seems quite robust regarding the syntax. I think that capturing the rotational parts and translational part of the Jones symbol in a single shot is not possible using std::regex due to the regex grouping that keep in memory only the last captured group (which is not the case e.g. for PhP regex implementation). That's the reason why I splitted the parsing in two steps. Could you please have a look on it when you have time and tell me if everything is OK for you ?