Removing troublesome black blotch

[afre (Alan)]

@s7habo

However, the patch based Impaint that Pat describes in his tutorial is very time consuming, and I then experimented with Multi scale Impaint for your example.

I believe multi-scale uses a faster implementation.

@David_Tschumperle

• Command matchpatch is a new and faster implementation of a patch-matching algorithm, and replaces the previous patchmatch command (still available though).
• Random number generator used by G’MIC now support multi-threading. Each command/filter using random numbers should be faster now (command matchpatch is especially concerned).