[pynt-devel] "exec" statement

[<mpf...@Th...>]

I've added a statement to let you run external programs. For example, the 
following will run the compiler:

exec "javac Foo.java"

I also added a PyntAST class, which has a convenience method for throwing 
a PyntException with the line and column numbers fill in. I still need to 
change all of the AST classes to extend this class (indirectly), and 
change all the places where we throw exceptions to use the error() 
method...