Implement game objects removal, move out charge logic from weapons

[pkulev]

Closes issue(s): [ #59 ] Related to issue(s): [ #52 ]

Description of the changes:

This PR makes two major changes:

• Split Weapon into Weapon and Charge (as separate renderable entities)
• Implement game objects removal

Both of them lead us to adding GAMEPLAY! Pew-pew and homebrew gameovers can be implemented as well as exposions. This is really great good news.

• What's new:

  • weapon and charge are separate entities
  • remove objects via State's remove method (now it's only InGame state, but will be moved soon)
  • current Application accessible via application.get_current()

• Fixes:

  • fix logging to stdout
  • fix formatting, docstrings

• Refactoring:

  • refactor weapon

[codecov-io]

Codecov Report

Merging #60 into master will increase coverage by <.01%. The diff coverage is 51.79%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
+ Coverage   62.56%   62.57%   +<.01%     
==========================================
  Files          40       41       +1     
  Lines        2089     2175      +86     
==========================================
+ Hits         1307     1361      +54     
- Misses        782      814      +32

Impacted Files	Coverage Δ
xoinvader/common.py	100% <ø> (ø)	:arrow_up:
xoinvader/collision.py	100% <ø> (ø)	:arrow_up:
xoinvader/tests/test_weapon.py	57.14% <0%> (ø)	:arrow_up:
xoinvader/gui.py	0% <0%> (ø)	:arrow_up:
xoinvader/sound.py	48.78% <0%> (-2.51%)	:arrow_down:
xoinvader/ingame.py	0% <0%> (ø)	:arrow_up:
xoinvader/application/__init__.py	100% <100%> (ø)	:arrow_up:
xoinvader/tests/test_application.py	100% <100%> (ø)	:arrow_up:
xoinvader/tests/test_state.py	100% <100%> (ø)	:arrow_up:
xoinvader/render.py	37.03% <33.33%> (+5.03%)	:arrow_up:
... and 4 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update c1e56ae...ed994c2. Read the comment docs.