Switched STL Quicklook plugin to VBOs.
Automatic platform size and automatic centering of previewed object
GCode Quicklook plugin: Better preview generation code (5D) and automatic platform size and centering
Fixed extrusion color changes (i.e. new color for each extrusion on/off change) for 5D code
Re-enabled correct color codes for legacy gcode (M101/M103 extrusion on/off)