Initial kodi name change

This is far from complete but its a start.
Switches most of the executables on Linux from xbmc into kodi.

This doesn't contain any cleanup of the code to make this easier next time or alters folders so most is still xbmc internally.
hmm, do we (still) need this? Specially since the default install prefix is /usr/local
From a quick grep only Util.cpp uses it for some HOME_DIR stuff, but setting this is/should be handled elsewhere. 
same below.