store image resources (like sprites) in methods [1]

[benrobby]

As a SWA student I want to be able to sync my resources using monticello, hence they have to be stored in the image.

Acceptance:

• [x] resources in our own imageloader and soundloader are stored in this format
• [x] resources can be loaded, encoded and synced

[benrobby]

estimation: 6

[NiklasKoehnecke]

decoding onto disk is not necessary once you have it in the methods. If wanted we can add it, but we see it as dead code

[NiklasKoehnecke]

time needed: 1

[ekrebs5]

accepted