Add type hinting based on annotations PEP-0484

[emacsway]

• https://www.python.org/dev/peps/pep-0484/
• https://www.python.org/dev/peps/pep-0483/

[mcepl]

Just to throw here davidhalter/jedi#630 (comment) ... merge requests based on this idea would be probably considered.

@aligrudi , what do you think?

[emacsway]

@soupytwist , can you assign this ticket to me, please?

[emacsway]

New in Python 3.5:

• https://docs.python.org/3/library/typing.html
• https://hg.python.org/cpython/file/3.5/Lib/typing.py

[emacsway]

Blocked by #150 and #186

[emacsway]

#150 is done in #187