Adding ELPA to Emacs core

[Phillip Lord]

I've had a bit of a play at allowing ELPA packages to be directly
distributed with a core emacs installation. I tried this before where
files from ELPA were adding into the core as package.el packages. This
version does something simpler -- the raw files are just dumping into
the Emacs core, and then loaded like normal.

It currently uses some heuristics to achieve this, but it supports
installing the package, any tests into EMACS/test/lisp and texinfo
files. I've added an extensibility point though -- packages could
control their own deployment where something complicated needs to
happen.

Currently, it's make file driven (i.e. you edit the make file to add or
update a new package), but it would probably make sense to put the data
in a different file.

It's on branch elparized-core. Comments welcome.

Phil