[-] Quaternions
[X] Draw rotated pixels in src order
[X] Use atan2 at beginning and end of line.
    Interpolation in-between values
[X] Test pixel perfect 90
[ ] Fix out-of-bounds pixel set

[ ] Optimization for square images?
[X] Fixed point computation?
[-] -funroll-loops

# Cache
[-] Rotate per channel -> no gain
[ ] Load pixels in 64-bit variable
[X] Cut image in tiles
 [X] Overlap
 [-] Rotate in one temp tile then copy/move it
 [X] Align tiles in memory
[-] Align memory -> no gain
[ ] RGBX format
[ ] Spiral layout?

# Quality
[X] Interpolate using SIMD, SSE (no big gain)
[ ] Image borders