If ProcessManager::execute_process() returns undef,
then the loop in Interpreter::interpret() thinks that
the command didn't get handled, and so goes on to look
for other commands. This is now corrected.
Bot output now appears in `recall` and can be `grab`bed.
Moved truncate_result() a bit further down to truncate after target nick
is prefixed to output.
dehighlight_nicks() was being invoked after truncate_result(), therefore
inserting \x200b zero-width space Unicode characters AFTER the message
was truncated.
Solution: moved dehighlight_nicks() to immediately preceding truncate_result().
Instead of "... [truncated; see http://xxx for full text.]" it more
concisely says "... <truncated; http://...>".
Increased irc.max_msg_len from a very conservative 425 to a more
generous 460. If you have very long channel names or nicknames, or if
you see things being truncated incorrectly, reduce this value.
