reorganize

new file Ktheory/Equivalences.v
fix the makefile

This fixes a bug I don't understand at all.  The symptom is that "make"
goes into an infinite loop reading the Makefile in sub/coq, even though
the recursive call has the arguments "-f Makefile.build".  Renaming
the Makefile first fixes it.  I don't know why.
Merge pull request #4 from UniMath/master

Update