Gametype refactor

New:

• Added gametypes[] to Lua
• Made possible to replace gametypes through SOC
• Turned rankings_type into its own enumeration, RANKINGS_

Fixed:

• Fixed some code that ignored if the gametype had spectators

Backwards compatible:

• Nothing to add

Backwards incompatible:

• Nothing to add

Lua gametype fields:

Field	Description	Returns
name	Name	string
rules	Rules	GTR_ enum
type_of_level	Type of level used	TOL_ enum
intermission_type	Intermission type	int_ enum
rankings_type	Rankings type (for HUD)	RANKINGS_ enum
point_limit	Point limit	integer
time_limit	Time limit	integer