xfer: fix freeze/problems when sending empty files with DCC (closes #53)
Merge pull request #56 from l/translation_ja

core: update Japanese translations
core: update German translations
doc: update German and Japanese auto-generated files
irc: fix description of arguments in infolist "irc_nick"

Only the nick is optional is this infolist (server and channel are required).
core: update German translation
core: add non-breaking spaces in French translations