Editor UI

[voylin]

PR for creating the editor UI. This will take a bit of time to set-up correctly, but I'll be keeping this up to date and push my changes (probably) every day.

TO-DO:

• Save layout (offsets, panel positions, ...);
• Add side buttons (file system, editor ui, render menu);
• Make panels display correctly inside of each container;
• Make it look nice (not needed).

For future versions, people will be able to add custom tabs on the left bar which will each have their own layout which the user made. This is needed to be fully modular, but a worry for later

[voylin]

Closed and re-opened as I was having upstream issues ^^"

[voylin]

Update for editor (non-pushed changes):

EditorUI will be the handler for the different screens (file manager, editing, render menu, custom, +++). The basic Editor layout will be something people can customize to their liking and create multiple layouts with (For subtitling, color grading, cutting, ...)

Still a work in progress, but don't expect this change to take too long. Also adds to the modularity of the editor as people will be able to make their own layout styles so they are not bound to the current layout of left|middle|right panel containers.

[voylin]

Made a quick update to printer which I'll be including in this PR.

[voylin]

I'll be merging this PR for now, there are TODO's in the code which will be done at a later stage as they aren't specifically needed at this point in time.