Move mpvcore/player/ to player/
Rename mp_core.h to core.h

Get rid of the mp_ prefix.
Rename mp_lua.c/h to lua.c/h
Move mpvcore/input/ to input/
Move libquvi stuff to stream/resolve/
Move options/config related files from mpvcore/ to options/

Since m_option.h and options.h are extremely often included, a lot of
files have to be changed.

Moving path.c/h to options/ is a bit questionable, but since this is
mainly about access to config files (which are also handled in
options/), it's probably ok.
Merge mp_talloc.h into ta/ta_talloc.h
Split mpvcore/ into common/, misc/, bstr/