Add window/fulscreen toggle

[spaghetticodefactory]

PR for #6

• Added window mode/fullscreen mode toggle functions
• Connected all signals in code.

[quellus]

How feasible is to add a toggle to the menu in the app as well? Should this be a separate issue?

[spaghetticodefactory]

How feasible is to add a toggle to the menu in the app as well? Should this be a separate issue?

• refactored everything to a WindowManager singleton.
• added toggle button to app menu
• cleaned up all signals from GUI to code
• cleaned up function names
• cleaned up label names
• added amplifier & input compression for a more stable input signal.
• added necessary gui for gain control
• added (debug) label for current input gain display to app menu

Sorry for the huge PR. I should've branched it properly.

This PR also implements #2

[quellus]

Committed part of this PR in #45