Issue #22: get all tests passing for Seaside3.1.1 in GemStone 3.2

- remove ExecutableBlock methods from Seaside-GemStone-Core package
- move UnorderedCollection>>restoreFromSnapshot: and
  UnorderedCollection>>snapshotCopy into Seaside-GemStone320-Core (new package for
  3.2) and Seaside-GemStone300-Core (3.0 and 3.1)
add GemStone 3.2 to lineup
Merge branch 'issue_22' into gemstone3.1