prepare release 1.2.15

prepare new release

remove mention of sage-brial from the README file

version bump for change in test suite

update m4 macro and configure.ac. Bump version for release.

Bump to version 1.2.10

bump to version 1.2.9 for new maintenance release

bump version to 1.2.8 for release on Monday

bump to 1.2.7

Version bump to 1.2.6 for release