Add specs for error inside to_hash of keyword args
Improve keyword arguments coercion and fix GC crash
Add extra padding for ByteArray after encoding
Add corner-case spec for ill-state string with no padding ByteArray
Removed obsolete agent mspec option.
Removed --agent flag from spec runs.
Removed obsolete Rubinius configuration for agent.
Singleton classes can't have subclasses.
Removed -X19 from specs.
Applied ryoqun's patch for JIT args. Fixes #3114.
Turn off JIT when halting.
Merge remote-tracking branch 'ryoqun/keyword-arguments-coercion-gc'
Merge remote-tracking branch 'ryoqun/encode-byte-array-padding'