Expose ini_getl and ini_getbool parsing code

[ITotalJustice]

Hi, thanks for making such a great library, i use it in many of my projects!

I was wondering, would you consider exposing the parsing code for long and bool such that it accepts a string and a default value and returns the result.

The use case for this is when using ini_browse to load all the configs. It would be nice to pass that value string to minIni and have it handle the parsing for us. I have done this in one of my projects here https://github.com/ITotalJustice/sphaira/blob/89fbb10ee60c873a7e756db6416391008ca79ae6/sphaira/source/option.cpp#L13-L30 but i thought i'd open an issue for it as i'm sure others would benefit also.

Thanks!