mingw64: done porting in e directory
mingw64: done porting in system directory
mingw64 port: ntl, system
mingw64 port: miscellaneous, attempting to link M2
mingw port: libxml is static, and the compiler needs to know!
mingw port: M2 links
fix stripping; fix gfan, not prepared for backslashes in argv[0]
mingw: fix gfan, part 2
mingw: disable pari at runtime if gmp uses the wrong word size; fix later
Moved code around so it will compile without FFPACK, FLINT enabled.
clean up a makefile by removing some old stuff
Merge branch 'release-1.6' into release-1.6-mingw
3 makefile changes to not echo etags, protect-configs and M2 link line.

These were made since the compilation in emacs24 for me was being
non-robust with these very long lines in the *compilation* buffer.
Added hash value support for ring elements.

For some reason, this had never been done!  Some rings, notably polynomial
rings and Schur2 rings, as well as tower rings, have place holder hash
functions.  Also, the hash function is created at RingElement creation
time: we might want to change this.
Had a typo in an assert, which caused M2 to not compile in debug mode
fix the "deb" distribution Makefile so "make clean" always works
fixed a bug where ring().clear was being called too early.

It was being called explicitly, and then called when the matrix
went out of scope.
DMat and SMat no longer refer to the type "Ring".  Part of DMat refactor

This is instead in the MutableMat class.
Removed get_CoeffRing in favor of ring(), in DMat, SMat.
Moved elementary dmat row+col ops to MatElementaryOps.

This class also has insert/deleter rows/columns.