*cmp_to functions of the String class should be consolidated

[the-sink]

It feels kinda weird to me that there are two separate String comparison functions to change whether the comparison should be case sensitive or not (casecmp_to and nocasecmp_to), and I thought it would be nice if these were consolidated into one compare_to(*p_str, bool case_sensitive=false) function. The non case-sensitive function appears to be used more often in the engine itself, and I would imagine this is the case for most projects as well, so case sensitivity should probably be off by default.

I wasn't so sure about naturalnocasecmp_to though... Perhaps ncompare_to with the same case sensitivity option added?