Bug fixes:
New features:
- New rendering logic: all instructions now draw on a shared layer-specific bitmap.
- To complement the feature before, Shape, Image and Text instruction have received a "Draw Once" option (since they have either a transparency option or antialising).
- Shape instruction! (line, ellipse, rectangle)
- Preset manager (all credits to zCri)
- Failing instructions now report exception to user and are automatically removed.