compiler/libec: Fixed warnings in generated code for incompatible pointer types

compiler/libec: Fixed warnings in generated code for incompatible pointer types
- Extending class objects casts to operator expressions in addition to args
- Silencing passing pointers to a function expecting a void ** arg
- Casting to void * when passing as typed_object &
   (Should really be a void * rather than a void **, but that might require
   tweaking code generated for classes methods if not already explicitly casted)