[ 537373 ] Demo files load foo.mc



Now load paths work, it is time to revisit bug [537373] Demo files load foo.mc

Quite a few of the demo files load("foo.mc").  This needs to be
changed to load("foo.mac") or load("foo"). 

Some examples are: 
- matrix/eigen.dem 
- simplification/functs.dem 

Does anyone have a preference - load("foo") is shorter.
I will fix them once a decision is made.