- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r293048,r293444:

r293048:

- Use a temporary file for the temporary md(4) devices instead of
hardcoding it
- Remove the temporary file in the cleanup routine

r293444:

- Move functions that might be used in class-specific cleanup functions
(geom_test_cleanup, etc) down so the testcases don't emit noise when
bailing
- Conform to the TAP protocol better when dealing with classes that can't
be loaded and with temporary files that can't be allocated for tracking
md(4) devices.

MFC r293028,r293029:

r293028:

- Use geom <class> load instead of g<class> load; g<class> doesn't exist
for all geom classes, e.g. geom_uzip(4)
- These tests require root. Skip all of the tests if they're run as non-root

r293029:

Add functions for managing md(4) devices and cleaning up said md(4) devices

These will be used soon in the various test scripts that source geom_subr.sh

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add file with helper functions for geom tools regression tests.