Rotation for brushes

[Esshahn]

Done:

• mirror H
• mirror V

Open:

• rotate by 90 degrees

[nurpax]

Note: realized that at least for rotation, the rotation code cannot keep rotating the same brush contents 90 degrees at a time.. Rather it needs to capture the original brush and then rotate 90, 180 and 270 from the original source. Otherwise switching between these rotation angles will be lossy.

[Esshahn]

Exactly