emacs: set limit of "long answer" to 10k.
emacs: merlin-seek can now send seek exact/end commands.
emacs: fixed merlin-send-command-async.

The callbacks were called in the temporary buffer created by tq. It is
weird that tq does not handle itself to restore the original buffer.
emacs: when using "quiet" way of telling merlin, check for the errors before the current phrase.
emacs: cleaned merlin debug output.