Callref bugfix in interpreter and compilers + autosav

Callref bugfix in interpreter and compilers + autosav

~~~~nitish
class A[E]
	fun foo: A[E] do return self
	fun bar: Fun0[A[E]] do return &foo # it didn't work before
end
~~~~

- Fixed a bug when `self` was a generic class with unsolved type. It was
impossible to return a callref, since the typing rule were not properly
executed.
- Added a test case in `test_callref.res`

Signed-off-by: Louis-Vincent Boudreault <lv.boudreault95@gmail.com>