Implement SET_TEXT_DROPSHADOW in ScaledText

[justalemon]

SET_TEXT_DROPSHADOW allows you to make a more customizable drop shadow than SET_TEXT_DROP_SHADOW.

[kagikn]

I noticed this issue now, but you assumed wrong. SET_TEXT_DROPSHADOW just does the same thing as SET_TEXT_DROP_SHADOW unless a non-positive value is passed as the 1st argument. The 2nd to 5th argument is marked as UNUSED_PARAM in commands_hud.cpp and the native implementation doesn't even use none of them. If the 1st arg is not positive, the drop shadows is removed for the next text draw.

I wish I noticed the wrong assumption before releasing any stable releases tbh...

[justalemon]

Oh, I didn't checked commands_hud.cpp before committing, I used Dot's NativeDB.