Multiple Fixes (frametiming, blending issues, steam deck instructions, IDE license)

[tulpenkiste]

Fixes:

• Steam Deck install instructions missing on unstable branch
• IDE failing to compile due to linked file
• Pacman Key usage in Steam Deck instructions missing -- before init
• Fixed bm_sub being overriden by bm_mod (missing breaks)
• Fixed docs/constants.md having the wrong blend modes.
• Improved frame timing

[tulpenkiste]

Now fixes issue #41.

Note: if merged, STA and test/blending.nut will need fixing to accommodate for the binds.cpp fix.

[tulpenkiste]

Converted to draft, going to fix open issues

[tulpenkiste]

Should fix issue #34 now.

[tulpenkiste]

Now fixes #33.