v0.9.1: Release 0.9.1(β)

Small update, mostly internal refactoring and improvements on CI

Code
* Added a lot of type hints.
* Types are checked through mypy now.
* Windows version uses angle instead of glew backend.

Bug Fixes
* Fixes images on windows executable.
* Fixed not finding config.ini on windows executable.
* Pins are slightly bigger.
* Fixed Smart bubble crash regression.

Packaging
* Added more classifiers on pypi package.

Continuous Integration
* Windows executable are now built on appveyor.
* Mypy checking on travis.
* Mypy checking on appveyor.