#850: Avoid preg_replace() with PREG_REPLACE_EVAL

All credit goes to Otomatic
#850: updating ucp_preg_replace function

All credit goes to Otomatic
Adding a wrapper for ucp_preg_replace
Appling ucp_preg_replace_callback
Merge pull request #74 from adaur/master

#850: Avoid preg_replace() with PREG_REPLACE_EVAL