Register taxonomy in constructor
Register post type in constructor
Fix regex sometimes causing stack overflow

Also change some checks and allow 0 in template tags.

The PCRE recursion limit is set to 100,000 by default, when it in some
cases need to be as low as 524, depending on the application call stack
size. Excellent answer on Stack Overflow (hey!) going deep into it:
http://stackoverflow.com/q/147052/2406900
Don't validate empty values
Use default action priority
Update plugin header and version to 1.1.1
Update documentation