Removed old comment
Hand absolute path to execfile for more useful tracebacks
Zip file containing input files for output-only task and slight simplification
Save sample test case in sum*
Templates are now ordinary classes

They do not get any local or global variables, etc.

The event handling mechanism has been removed as it is hopefully
no longer necessary.
Moved some contest-independent utility functions

(from AbstractConfig to Supplement.py)
Templates don't have to be BasicConfig objects any more
Moved constraints handling from PlainTemplate to TaskConfig