Make avatar respect maxspeed lerp, allow changing speed multiplier via script. Some extra functions.

Add one additional not-timed speed multiplier that also ignores influence by currents.
Lua functions added:
- avatar_setSpeedMult(num, time)
- avatar_setSpeedMult2(num)
- avatar_getSpeedMult()
- avatar_getSpeedMult2()
- entity_isInCurrent(entity)
- entity_getNumTargetPoints(entity)

Aquaria/Continuity.cpp

@@ -3209,6 +3209,7 @@ void Continuity::reset()
 	//worldMapTiles.clear();
 
 	speedMult = biteMult = fishPoison = defenseMult = 1;
+	speedMult2 = 1;
 	poison = 0;
 	energyMult = 0;
 	light = petPower = 0;