X11 "cross" cursor as cursor in Draw-mode

[sp1ritCS]

No description provided.

[blackhole89]

I don't think I prefer this over the pointer (which allows you to see what you are drawing more clearly since it only occludes the bottom right corner of it), though making it configurable would be an acceptable option (perhaps gated on introducing a config dialog, which has been in the pipeline).

[sp1ritCS]

I think it makes more sense for the "pen" cursor to be a cross, as you can see where you are drawing and I find the "default" cursor irritating if I try to draw something.
Having a config option to set it would be great.

[blackhole89]

Subsumed by #59.