set a coomon variable for extra compiler arguments
the 3_ala test case data was missing from the repository
xcamshift didn't build with the old xplor ensemble interace

at some point between 2.31 and 2.35 the interface to the ensemble
routines changed in an incompatible manner. Add some conditional
compilation to cope with this
Merge pull request #63 from locsmith/alvin_bug_3

Alvin bug 3