Extend point_bugbait functionality

[arbabf]

This PR adds a SetRadius input to point_bugbait, as well as a new functionality that allows point_bugbait to use mins and maxs. This is a super-niche situation where spheres don't work well but a big box does. It annoyed me enough for me to add such a functionality.

Possible uses for this:

• Throwing bugbait into areas (like big targets, or hallways) where a sphere would allow the output to be triggered erroneously (e.g. on the other side of a brush), but smaller spheres miss a small area (and/or take up many entities)
• Squeezing bugbait while standing on a platform or set of platforms
• Dynamic point_bugbait zones that change depending on gamestate.

One could theoretically use a trigger_multiple with a filter set to npc_grenade_bugbait, but this only covers thrown bugbait and would need to conform to the geometry very tightly, making it somewhat infeasible.

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Does this PR close any issues?

None.

PR Checklist

• My PR follows all guidelines in the CONTRIBUTING.md file
• My PR targets a develop branch OR targets another branch with a specific goal in mind

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FGD entry:

@PointClass base(Targetname, Parentname) size(16 16 16) wirebox(bmins, bmaxs) sphere(radius) color( 255 255 0 ) = point_bugbait : "Bugbait sensor point"
[

	Enabled(choices) : "Start Enabled" : 1 =
	[
		0 : "No"
		1 : "Yes"
	]

	spawnflags(Flags) =
	[
		1: "[1] Do not call antlions to position" : 0
		2: "[2] Don't activate on thrown bugbait splashes" : 0
		4: "[4] Don't activate on squeezed bugbait" : 0
	]
	
	useradius(choices) : "Use Radius Keyvalue" : 1 : "If disabled, use mins and maxs." =
	[
		0 : "No"
		1 : "Yes"
	]
	
	radius(integer) : "Sensor Radius" : 512
	
	bmins(vector) : "Mins" : "0 0 0"
	bmaxs(vector) : "Maxs" : "0 0 0"

	// Inputs
	input	Enable(void) : "Enable the sensor."
	input	Disable(void): "Disable the sensor."
	input	Toggle(void) : "Toggle the sensor."
	input 	EnableRadius(void) : "Use the Radius keyvalue of the sensor."
	input	DisableRadius(void) : "Use the mins/maxs keyvalues of the sensor."
	input	SetRadius(integer) : "Sets the radius of the sensor."
	input	SetMins(vector) : "Sets the mins of the sensor."
	input	SetMaxs(vector) : "Sets the maxs of the sensor."

	// Outputs
	output OnBaited(void) : "Fires when bugbait lands within a radius of the sensor"
]