Blender Git Loki

The following updates have been contributed by Willian P. Germano:
* Implemented BPY_end_python function.
* Implemented error handling. This results in rerunning a script after an
error has occurred. No need to restart blender anymore.
* Camera module supports dir()
* variable assignment now calls the Python equivalent function - this has
type checking and should be safer now.
* Implemented the Lamp module. Used the Camera module as a template.
* Implemented the Image module.
* Added EXPP_ClampFloat and EXPP_intError functions to gen_utils.[ch]
* Implemented 'constant' object.