Mininum velocity for teleporter exits

This MR implements g_teleport_minspeed cvar to accompany already existing g_teleport_maxspeed cvar.

This makes it so that we are also able to set exit speed instead of bounding it between 2 if the values are identical and allows for example Quake 3 compatibility.

First min speed is calculated and then max speed is calculated. This implementation respects maxspeed more, therefore if min is 1000 and max is 500 it'll always set exit speed to 500.

I set physicsQ3.cfg and physicsCPMA.cfg to set speed to 400, I don't know what values other games should have so I set min 0 where I saw another max 0. For physicsXDF.cfg I made a poll in exe.pub Discord server which is the dominant XDF community at the moment, they voted 7 votes for min 0 max 600 (no change) and 1 vote for set 600 consistent exit speed.

Configuration Examples:

min 400 max 400: in ??? out 400 always, Quake 3 compatibility

min 400 max 600: in 300 out 400

min 400 max 600: in 526 out 526

min 400 max 600: in 700 out 600

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min 000 max 600: in 300 out 300

min 000 max 600: in 526 out 526

min 000 max 600: in 1700 out 600

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min 600 max 000: in 300 out 600

min 600 max 000: in 700 out 700

min 600 max 000: in 1700 out 1700