Reported by David Roy
When <instance_node>s where read, their transformation matrix got overwritten with the transform matrix
of their own node, not taking into account the parent node transformation. Instead of doing
that we now get the parent node transformation matrix and apply it to its own, and prevent
caller from overwriting this new transformation matrix.
- object updates were not being flushed, so children weren't updating.
- apply the matrix relative to the parent, added this as an option to object_apply_mat4() which allows assigning the worldspace matrix in python without worrying about the parent.
fix included in report from Martijn Berger (mberger)
made some small changes.
- use ints rather then unsigned long for printing, values are not likely to be very large.
- CMake remove strict flags from collada build dir since I had warnings in the collada headers.
- added xml2 to collada libraries else I couldnt get collada building.
