Use proper interface to add fake Import object
Support alias in _make_fakeimport
Implement the case where raw object is an instance

There is still a bug in this implementation.
The corresponding test fails.
Fake imports should locate before fake statements
Fix test_complete_raw_instance example

'dt.strftime("%Y").up' does not work even if with `api.Script`.
Change it to the one that can be handled by Jedi.
Document api.Interpreter
Document _import_raw_namespace more
Support case like `from os.path import join as pjoin`
Document api.Interpreter._genname