Log Message:
gama: Update to 1.20

packaging change: Depend on GNU make (not documented upstream).

Upstream changes:

* New test suite for matvec classes and support for valgrind memory
  leak tests for tests/matvec and tests/gama-local.

     This release is a preperation phase for the next release in which
     the base matvec memory handling class (MemRep) will reimplemented
     with C++11 move constructor and move assignemnt operator.