- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

MFp4:
Add support for read-write parameters. Allow an optional initializer
for read-write parameters. Print the value of those parameters on
success following the PASS.

o Extend the suite to run more than just the driver. We need to run
mdconfig(8), because we need a disk to work on.
o Extend the number of tests now that we have a disk.
o Simplify the driver. All parameters are ASCII strings now.

Add the beginnings of a testsuite for testing GPT control requests.
The testsuite is based on a simple driver program that builds a
request from the arguments passed to it and issues the request to
Geom. The driver emits FAIL with the error string or PASS depending
on whether the request completed with an error or not. A -v option
has been added to the driver and causes the request to be dumped.
The -v option to prove(1) controls the -v option to the driver.

The testsuite itself contains a hash of which the key constitutes
the arguments and the value is the expected result.