core: add support for negated tags in filters (closes #72)
core: add parentheses around tests in conditions
core: add support of '!' for tags in /help filter
core: update ChangeLog (add support of negated tags in filters)
relay: fix disconnection of client on empty websocket frames

WeeChat disconnects any client when a frame with length 0 is recieved.
relay: reformat comment
core: update ChangeLog
irc: add support of message 324 (channel modes) in option irc.look.display_join_message (closes #75)
relay: add message "_buffer_cleared"
core: remove line in ChangeLog (add of "#" in front of channels on /join)

The new option has changed the behavior again, so "/join 0" will now
part all channels by default.
core: fix memory leak when restoring buffers after /upgrade
core: do not restore title of core buffer after /upgrade
core: add comment
core: update German translations
api: change type of arguments displayed/highlight in hook_print callback from string to integer (in scripts)
doc: update German auto-generated files
doc: fix pylint warnings in docgen.py
core: add pylint check of doc/docgen.py (Travis)
doc: fix continued indentations in docgen.py
core: add clang compiler for Travis build