better treatment of embedded files

Addresses https://groups.google.com/forum/#!topic/spire-math/EwdTSUdSDhI.
After this fix every library that uses paradise will have its own copies
of embedded files, regardless of the classpath it was build on.

Also establishes a versioning scheme for embedded files in order to
prevent situations when multiple libraries with incompatible versions of
embedded files end up on the same classpath. So far only QuasiquoteCompat
is versioned, because Liftable isn't expected to be volatile.