Don't sort cheat database after load

The entries in the cheat database have to kept in the order in which they are
read or otherwise the preconditions prefix the wrong writes to memory. This
leads to hangs and crashes for multi code cheats.
Allow multiline cheats for non grouped cheats

The list of codes of a multi code cheat without a category were overwritten
each time by a an empty list. This made these non-working or even let the
emulated rom hang.
Unify the way the cheat code lists are initialised
Sort the cheat groups in the cheats menu