use internal gamepad library

[philschatz]

This adds an internal gamepad library similar to contro but provides the following features:

• uses the standard layout to refer to buttons and sticks
• supports gamepads that do not use the standard layout
  • some browsers like Firefox do not provide a standard mapping
  • uses mapping files to support non-standard gamepads
• allows checking if a specific button is available on the gamepad
• allows composing buttons, sticks, and even gamepads to make it easier to write games
• allows scoping the key presses so they only apply when the game is in focus (being played)
• allows disposing of keyboard buttons when they are no longer needed

[codecov]

Codecov Report

Merging #90 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #90   +/-   ##
=======================================
  Coverage   46.71%   46.71%           
=======================================
  Files         144      144           
  Lines       12012    12012           
  Branches      854      854           
=======================================
  Hits         5612     5612           
  Misses       6228     6228           
  Partials      172      172

---

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 bd41b80...50badf3. Read the comment docs.