Organised scripts + "/scriptfiles/", new bag type

Rewrote the bag definition method so it's more like SafeBoxes. Bags can
be defined from items with DefineBagType much like the DefineSafeboxType
function. Also added a new bag type that holds 9 items and 5 large items
and is coloured green (with the new SIF update that enables item
colours)

Organised the "/SS/Core/Item/" directory a bit more, moved all the
scripts that contain more than just item related code to other folders.
This includes "backpack" (a whole feature, not just item code),
"medical" (multiple items' code), "repair" (vehicle related), "sign"
(Moved sign entity code out of here, left just the OnPlayerUseItem code)

Converted more gPlayerData and gPlayerBitData variable uses to functions
in preparation for making this data private and only accessible through
interface functions.

Moved some include lines for scripts under different comment categories,
now there are "Vehicle", "Weapon" and "Loot" categories.

Updated the scriptfiles folder, removed "/Cameras/" directory, added in
readmes for all the empty folders to ensure the folders actually get
uploaded.