Improve the release script before 0.2.0:

1) Only archive NEWS file on major and minor relesae, not bug-fixes.
2) Switch back to correct development branch during final release step.
3) Add do_svn_switch helper to ensure package variables are reloaded.


git-svn-id: svn://svn.berlios.de/openocd/trunk@2516 b42882b7-edfa-0310-969c-e2dbd0fdcd60