Mod support and modularity improvements

Hi guys,


As discussed in the forums, the intent of these changes is to improve the modularity and mod support for Sunrider.  This is done by using inheritance to create a new BM object, which will hopefully mean that people writing a skirmish mod (for instance) can do it without spamming if statements all through the main code.  This _should_ reduce the impact on the main code files in future.



Blue