Allowed source files to be in a subdirectory
Added parameter variables (that are not writable)

parameters can also be used to set the size of static arrays.
forthonf2c is now written out by wrappergenerator

Whereas before it was always written out when cfinterface was imported.
Minor clean up in wrappergenerator
Merge branch 'master' of github.com:dpgrote/Forthon
Updated README