Merge branch 'release-1.8'

and increment version number to 1.8.2.1

patch flint, as it was patched before, ...

... so it doesn't try to read the file of Conway polynomials

This will enable us to release 1.8.2

restore good caching behavior for GBs

Mike noticed that my recent changes to "remainder", part of making Hom
and related functions more general, caused it to stop caching the gb of
the denominator, slowing down example code that calls it repeatedly with
the same denominator.  Here we fix that.

The choice of keys for caching matrices derived from modules is
arbitrary, so feel free to review and change later.

increment version number to 1.8.0.1

increment version number to 1.8

Merge branch 'release-1.7' of github.com:Macaulay2/M2 into release-1.7

bump version to 1.7.0.1

bump version to 1.7

increase version number to 1.6.1.1

We tagged the previous commit with "version-1.6.1", to
indicate that it's relatively stable.

increase version number to 1.6.1

The linalg branch of Mike's has just been merged, and the
tests all pass.