jMonkeyEngine: jMonkeyEngine 3.4.0-beta4

From jMonkeyEngine: link to the original post

A non-production release for development and testing, which will hopefully lead to a "stable" release.

Noteworthy changes relative to 3.4.0-beta3:

• Bugs addressed:
  • MorphControl doesn't override JmeCloneable/Savable methods (issue #1548, PR #1549)
  • diagnostic messages from TestMusicPlayer (issue #1544, PR #1547)
  • crash in TestManyLocators (issue #1543, PR #1546)
  • crash in TestAppStates (issue #1542, PR #1545)