Added speed change to effect hub

Lagged movement can be centrally controlled in the effect hub. Speed ups
and slow downs are calculated against each other and are stored
seperately.

Plugins can change the time of the speed change.
Frost Pistol: Use effect library for slow down

Does not need to block the impulse upgrade anymore, because the speed is
subtracted correctly.

Also use the effect hub to change the player's color to blue and back.
Impulse: Use effect library for speed up
Frost Pistol: Fix typo
Shrinking: Fixed not resetting the effect when selling

When the upgrade was sold completely, level 0 didn't reset the player to
full size.
Gravity: Fixed not resetting effect when sold

When resetting to level 0 the gravity wasn't reset to 100%.