RFE: code review, several optimizations

Enclosed is my next version containing:

• further optimization: recognizes actions of bridged users with space in names (allowed in XMPP/jabber)
• parse and split of message changed to single regex (several REs combined, so processing is more precise and faster now)
• try to avoid recursion using cycle as long as possible (so can save nested calls for simplest cases if user message going over 2 bridges)
• doubly bridged client name (user host) contains both bot names now, e. g. ~user@bridged/ijchain/liberachain
• recognize whether user (behind bridge) changes its nick, so rename it by bridged message "userA is now known as userB"

Like previous PR, I rebased it from my branch (which I cannot abandon due to many changes, e.g. API used for my own automation, etc). So because of quasi missing common ancestor (you changing every time your version) and many conflicts, I cannot guarantee that I did not miss something by rebase/resolve process (indent, naming, formatting).