3D Brush and default model for every paintop

[LukasT.dev@gmail.com]

Hi,

I committed the 3d brush visualisation and now I would like to have default 3d 
model for every brush.

Current implementation is like this

I added virtual method display-list to paintop settings object.
kis_tool_freehand checks if returned display list is display list, if it is, 
it is painted. Display list is something like QPainterPath. Compiled opengl 
commands - cached model in this case.

1. solution was:
Move kis_model to krita/image/, not to libpaintop/ so that kis_paintop_setting 
can find it. brushengine/ does not link against the libpaintop/
kis_paintop_setting would load the default model and provide the display list.

KisModel is class which parses obj file and store it in display list.
It should be compiled only when HAVE_OPENGL is defined (this is not solved yet, 
how do I need to edit CMakeFile.txt in libpaintop?)

2.solution:
Paintop settings object will return QString with path to model.
Then kis_tool_freehand which is in krita/ui/tool/ needs to see KisModel.
Freehand would load and parse the obj file. So the KisModel needs to go to 
image/ or somewhere where it is more visible.

3. suggest your solution

Lukas