Battery swap

Features: 
Motorbike and car batteries install/remove without tools and with level 1 mechanics.
Truck battery install/remove with wrench and level 1 mechanics.
New vehicle parts: swappable storage battery case, swappable storage battery.
The case is installed in the same slot as a regular storage battery, lvl 3 mechanics.
The swappable battery is installed in the case, with level 1 mechanics.
Electric cars spawn with swappable storage batteries.
Storage batteries and swappable storage batteries installed with the 'storage battery' part.
Can still weld storage batteries into the car.

Old OP:
Implements a TOOL_NONE and TOOL_WRENCH flag to vehicle parts that means a part can be installed/removed without a tool or only a wrench, respectively. For example, to install and remove a truck battery without requiring use of a welder, or duct tape. Storage battery and small storage battery have the TOOL_NONE flag, while other batteries were given TOOL_WRENCH flags. 

This required a change to the install process, where a parts list is now shown after i is pressed, even if you have no appropriate tools. The same goes for the remove process. 

Each individual item will show what tools are required before pressing the enter key.