It works for me, so maybe you find it useful too.
It covers (almost) all Lua 5.2* and LÖVE 0.9.1 functions, including return values, parameters, their types and short hints from official documentation. Also it contains deprecated functions from LÖVE 0.8+ for migrating users, with note of what functions to use instead.
Class methods are included into AC as well, but they can't be used directly (you should rewrite class name with your instance name every time) and thus they're useful only as shorthand documentation.
Another file (langs.xml) is an updated syntax highlighting config, so Notepad++ will highlight love.-functions as well as common Lua-functions.
And the last file (functionList.xml) is for Function List sidebar.
It's still raw and definitely far from perfect, so let me know if you find something to repair.
Oh, and don't forget to enable Auto-Completion in NPP preferences if you decide to try.
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* Note that Lua 5.2 is slightly different from 5.1 used in LÖVE. In particular, 5.1 does not offer bit32-functions, and 'table.unpack' still called just 'unpack'.
Few samples:
