Fix italics syntax in BUILDING.md [skip ci]
Mark =~ and !~ methods as writing backref, for compiler use.

This is an additional fix related to #1041. That issue appears to
be fixed already without this change, but I still believe this
change is necessary.
Oops...uncomment part of spec for 1041 I was testing.
Cleanup: Deleted trailing whitespace on lines in ir/ directory
Merge pull request #1029 from Sinjo/fix_building_markdown_formatting

Fix italics syntax in BUILDING.md
Split up test_kumi so it can AOT compile for testing.
[IR] Specialized yieldSpecific code for common cases

* convertValueToArgArgArray is the generic code that converts
  yield arg(s) (as is or that has been recast into a RubyArray)
  into IRubyObject[] args array. This patch eliminated some
  unnecessary construction of a RubyArray object on some code paths

* Discovered this when I was looking at whether any of that code
  could be wrapped in IR instructions.
Field cleanup in RubyRunnable.
Fix conditional in $~ scoping spec.
Remove the special invokedynamic default case for IBM J9

Much like Oracle's JVM, IBM's J9 VM doesn't support invokedynamic
very well until 1.8.
Remove unused local variable
Fix framing regression.

During 1.7.5 dev cycle, I reworked how backref/lastline are
stored to reduce their impact on performance and bring their
behavior more in line with MRI wrt blocks. In the process of
making this move, I inadvertently turned on the frame requirement
for all core class method names, resulting in any Ruby code that
calls any of those names using a full frame. This has a serious
perf impact on many benchmarks.

This change fixes the framing to only be active when the target
method actually needs to read or write a frame field, reducing the
number of frame-requiring methods significantly and restoring
perf to what it should be.

We are unsure if this change will go into 1.7.5, given the wide
impact a mistake in this fix could have, but it is passing JIT
and AOT ruby19 tests and I will continue to test it to hopefully
get it into the release.
do not cache DEFAULT_OFFSET, it is not fixed for a given DateTimeZone (summer time)

* unfortunately, creates a Rational for DateTime.now (cache it? remove,lazy @of?)
Merge pull request #1053 from bruceadams/no-special-j9

Remove the special invokedynamic default case for IBM J9
Fixes JRuby #1047 - incorrect test for whether a kw arg was provided.

Formerly, the code attempted to extract the argument value from the
hash of provided values and test it against nil. This fails in the
case of an explicitly passed nil. The new version instead tests
whether the hash contains the desired key.
Add license header.
Fixes #1049: incorrect arity checking for kw arguments

There were two basic problems with the existing logic:
* Arguments could be treated both as kw args and as, e.g.,
optional args.
* An arity check for methods with kw arguments in the Arity class
is deferred to asignment time, but the check was not being performed
there, either.
Merge remote-tracking branch 'github/master'
Update versioning documentation
bump version