Rename PHPException to Throw

'PHPException' was ambiguous since it suggested that the object was
a wrapped PHP exception. 'Throw' indicates its status as the
implementation of the control flow jump that occurs when 'throw ...'
is executed.
Create Interpreter.throw()
Add interp.call_method()

This simplifies a common pattern:
   interp.getmeth(w_obj, 'method').call_args(interp, [w_arg])
becomes
   interp.call_method(w_obj, 'method', [w_arg])
in which the app-level call $obj->method($arg) is more easily visible.
fix
Merge pull request #63 from rlamy/easyOO

Easy oo