Update window bounds attributes on change

[maddie]

This commit depends on PR asticode/astilectron#55, and targets astilectron release 0.53.0 (yet to be tagged and released).

With the added listener and function, users should now be able to get the window's position and size in real time.

Should fix issue #127

[coveralls]

Coverage increased (+0.04%) to 78.607% when pulling faa47cf89912c752171a6053cacffd138ec855e3 on maddie:master into a95bcffcf5d4ac0a4017b4ad9bde0e990864aee3 on asticode:master.

[maddie]

The pushed code depends on astilectron 0.53.0 and CI fails to download it, so it fails :(

[asticode]

Cheers