0001291: plane offset precision is limited to 0.1
Set explicitly trackball as default orbit style
0001290: Add spiral tool in Part Module
+ Fix build failure with >= OCC 6.5.2
+ Add missing include
Drawing: Symbol command

A new symbol command and Drawing::FeatureViewSymbol object allow to
load the contents of an external svg file and place it as a symbol
on a Drawing page. This symbol can then be moved and rescaled.