release announcement draft

[Lukast dev]

Hello,

very nice announcement.

> <li>Some operations crash the OpenGL canvas</li>

Can you be more specific here, which operations?

> <li>The mask painting system still only uses opacity, instead of the gray value</li>

What is this? Which mask painting system? Brushes?

> <li>We are still working on a new set of default brush presets, so currently no good set of presets is preinstalled</li>

Btw for sketch bursh, please let the original presets there as they
mimic original harmony.
We need nicer icon for them. Same for chalk preset, that is installed
for legacy reasons.
Some people liked the chalk brush, but it can be mimicked with Pixel
brush, so I created
that preset to make it easy for legacy users. Also Silvio created some
default presets for color
smudge brushes that should stay - optionally with nicer icons :)