Remove sculpt/paint checks in getTransformOrientation_ex
This code goes back a long time (early 2.5x). I couldn't find any
reason why sculpt/paint checks were being made.
This makes the following changes:
- When in object mode, the object must be selected.
Since this function typically operates on the selected items.
- When in paint/particle modes, the objects matrix is always
used regardless of selection, since object selection can't be
controlled in these modes.
- When there is no active object, the first selected object is no
longer used as it's quite an arbitrary decision & not something
done elsewhere with objects in Blender.