unified directory for plugin translation files

[yojoe]

mvlcek: but still you are talking about lang directory inside plugin folder dir, and I had on my mind a unified directory only for lang files.
I thought a bit about it and /plugins/lang/ dir with plugin_name_language files may get a bit messed up pretty fast, so /plugins/lang/plugin_name/language_files is a bit better idea.

CC: I noticed that some plugins would be fine with translation variables provided in language files for GS.
Having this on mind what do you think about adding to http://get-simple.info/wiki/plugins:creation a list of basic translation variables, so plugin devs could just use them and their translations would be handled by lang file for GS automatically.
Rest of needed vars would have to be placed in stand alone translation file.

edit: at least encourage plugin devs to use vars already used by GS