Minor refactoring and encapsulation of constants, add .gitignore

[mags0ft]

Hello and good day,

I refactored a small amount of repeating code and constants and encapsulated these values in their new, own constants.py file - a file where everything that's related to non-changing values can be placed, so if something changes in the future, there's one central place to consult and edit!

For example, you do now have this handy Platforms class that keeps track of the sys.platform values of the platforms that aren't yet fully supported. Once every single feature works on macOS for example, you can simply remove it from the ported tuple and it'll be reflected in all of Alpaca.

Translators are also no longer in the main.py file but rather in the constants.py file, where they are in a more encapsulated space.

I also added a .gitignore file that allows other editors than GNOME Builder to work with the project more seamlessly.

Last but not least, I re-organized the imports of the files I edited.

Best greets! :)

[Jeffser]

Aight Thanks