Add deprecation warning to lock class
SI-7265 javaSpecVersion, adjust isJava... tests

Make this and related properties public, because they
are useful.

This change ought to have been committed at 2.11 and then
backported with restrictions, rather than vice-versa.

Note that they are defined in the order, version, vendor
and name, which is the order from the underlying javadoc.

It would be a neat feature of the PR validator, as previously
imagined, to run a "pending" test and then, on success and
merge, to move it automatically to the canonical suite.
SI-7737 Regex matches Char

Enables Char extraction by regex.

```
val r = """(\p{Lower})""".r
"cat"(0) match { case r(x) => true }
val nc = """\p{Lower}""".r
"cat"(0) match { case nc() => true }
```
Merge pull request #2780 from lcycon/lcycon-deprecate_lock

Add deprecation warning to scala.concurrent.Lock class
Merge pull request #2791 from som-snytt/issue/7265-2.11

SI-7265 javaSpecVersion, adjust isJava... tests for 2.11
Merge pull request #2819 from som-snytt/issue/regextract-char

SI-7737 Regex matches Char