rotscrnang/look_ang/return_to_center improvements

With all the Q16.16 and input updates, the look left/right buttons didn't receive any love.

Lastly, I had to move lastInputTicks to the playerdata_t struct. When first running P_GetInput(), the initial value of elapsedInputTicks is the actual value of timerGetHiTicks(), which is into the thousands. This high initial value was affecting how scaleAdjustmentToInterval() scales as it was taking an initial q16look_ang value of 512 and overflowing the fix16_t type, making it -32,768.

Please let me know if there's any changes that need to be made.