first cut PropertyHolder class
all Objects are PropertyHolders
expose fuel property for test
method to add properties to lua table
access properties directly from lua objects
back the property map with a lua table
don't predeclare properties, at least for now
make property map a field, and have one on each body. hackishly teach the lua dispatcher about it
explicit setter for char*
make Body tree inherit PropertiedObject to get its properties

Conflicts:
	src/LuaBody.h
	src/LuaCargoBody.h
	src/LuaEquipDef.h
	src/LuaMissile.h
	src/LuaObject.cpp
	src/LuaObject.h
	src/LuaPlanet.h
	src/LuaSpaceStation.h
redo Ship attributes as properties
complete properties
make sure properties get set up at ship init
change ship properties when the core values change too
property for Body.label
cargobody and missile attributes
clean up a couple of things
emit signals on property change
expose PropertiedObject to Lua
New combat music track (#2209)