Added xacro and macro_xacro for bmda3

Shaun - I updated two of the items that Gijs requested. The symmetry request will take more time than I have today.
I'm not familiar with this robot, so this is just a question: is it impossible to change eefs on this particular model? Cause the xacro seems to suggest this. Otherwise `tool0` should be made an intermediary frame / link between the `link_T` and whatever is the eef, imo.