Blender Git Loki

Export mutiple objects; remove unused fstream.

Adds support for multiple objects to be exported from a frame.
Also checks for them to be OB_MESH types. More object types need to be
supported yet.

Renamed data_to_export to more fitting, object_to_export of which we
use vector to contain all exportable objects.

Remove unused fstream based file writer since fprintf is consistently
faster.

Also reduce function calls of fprintf since lengthy arguments were
already removed.