Reuseing allocation when?

[p0nce]

• try to reuse former allocation when chaining create functions, often the former allocation is forgotten for no reason... But reusing the allocation is perhaps a prime reason to reuse the Image?

• allocating storage should return a slice, and take a slice for former allocation

Is realloc worth it vs free+malloc? Sometimes yes.

 // PERF: on Windows, reusing previous allocation is much faster for same alloc size
    //       314x faster             vs free+malloc for same size
    //       10x faster              vs free+malloc for decreasing size 1 by 1
    //       424x slower (quadratic) vs free+malloc for increasing size 1 by 1
    //       0.5x slower             vs free+malloc for random size

If we store the allocation as slice, we could second guess realloc().

[p0nce]

• currently a problem for Dplug, recreating an image buffer should reuse the allocation