Merge pull request #252 from l/translation_ja

core: update Japanese translations
doc: update Japanese auto-generated files
irc: add support for color codes 16-99 in IRC messages (closes #228) (patch from Nei)
irc: add infolist "irc_color_weechat"
doc: add IRC color codes 16-99 in user's guide
core: update German translations
doc: fix docstrings of functions
core: add debug message in hook_process when core debug >= 1
core: regroup libcurl constants/options by version
core: add constant for libcurl >= 7.38.0
doc: update auto-generated files with URL options
doc: update German auto-generated files
script: add option script.scripts.url_force_https (closes #253)
core: update German translations
doc: update German auto-generated files
core: fix display bug when scrolling in buffer on a filtered line (closes #240)
doc: update German documentation
relay: send messages "_buffer_localvar_*" and "_buffer_type_changed" with sync "buffers" (closes #191)
tests: add hashtable tests with multiple items giving same hashed key
api: return value in function command(), remove WeeChat error after command callback if return code is WEECHAT_RC_ERROR