Revert "LuaTable: remove unused GetMap() function"

This reverts commit 15bf44506a7c6ea515595566c4f994fd32549b4e.

Conflicts:
	src/LuaTable.h
new-equipment: Add modifiers support in Ship including mass handling.

The plan is to have new-equipment live alongside the old equipment
handling and replace bits by bits the old infrastructure.

Conflicts:
	src/Ship.cpp
	src/Ship.h
Shiptype: store the slot informations in an map<string, int>

This allows the system to decouple ship definition from the rest of the
Lua, thus returning to the previous state and easing any future
migration of the ship definition file format.

Conflicts:
	src/LuaModelViewer.cpp
	src/Pi.cpp
	src/Ship.cpp
	src/ShipType.cpp
	src/ShipType.h
new-equipment: Add an EquipType lua class.
Add a new lua library EquipSet.lua to handle equipment changes.

This new Lua class will leave alongside the old C++ infrastructure for a
little while.
new-equipment: Add an "equipSet" Property to Ship to hold the new lua EquipSet

Conflicts:
	src/Ship.h
new-equipment: export modifier handling to Lua

Conflicts:
	src/LuaShip.cpp
Replace Ship:GetEquipSlotCapacity by its Lua-implemented counterpart

Conflicts:
	data/libs/Ship.lua
	src/LuaShip.cpp