Expose the root data and symbols from testutil.get_scope_values.
execute implementation for FuncDeclStmt.

Creates a FunctionTemplate symbol and initializes it so that it's ready
to be called.

Of course, calling isn't actually implemented yet so as of this commit
there's not really much to be done with a FunctionTemplate symbol.
Report type mismatches on assign using type name rather than repr.

We should never be showing repr stuff in our error messages.
Fix some bugs in integer equals that crept in.

I guess this means we're missing some tests here but sadly I don't have
time to address that right now. :(