Implement a QOI decoder (for fun ;p)

[Dandielo]

Base on the reference implementation: https://github.com/phoboslab/qoi

Reasoning:

• To make a small challenge.
• Create an allocator base implementation that can be streamed.
• See if something can be improved.

[Dandielo]

An idea to check out was what if we reduce 'run' flags to 31 consecutive values and extend capabilities of 'diff'