v0.70 fixes - Abstract PCRE specifics and attempt to make pestr faster by pre-compiling hostname patterns.

These changes do not fix #60 - at least we know the cause - well, not completely :-(

If we don't find a solution for the aforementioned issue (unlikely), should we migrate from PCRE to:
-  [libc's regex](http://www.gnu.org/software/libc/manual/html_node/POSIX-Regexp-Compilation.html) - It does work with UTF-8, but does not support UTF-16 nor UTF-32;
- [ICU](http://site.icu-project.org/) - The fact that it's a huge dependency should (I think) be considered;