#248 units with zero "0" movement transportable

[sneakingcoward]

units with zero "0" movement:

existing:
there was a parameter "zero movement unit selectable".
but thats all, a zero move unit cant be transported...

proposal:
structural units like factory, etc... get as default a movement of "-1".
normal units can then get a "0" movement. with this they can be handled as a normal unit (selectable) and transported by sea, air and land.