Embedded perl is now a class

Also added a virtual base which contains a very simple interface to each
language:  one method.  Constructor gets everything set up, execute runs
the language for each line, and destructor gets rid of the interpreter.
Simple.

Also we're no longer doing a bunch of library loading and crazy stuff
within the language module - we can just link to the library in question,
and call the functions directly.  I think I was just trying to be too
fancy for my own good originally.