Review: Mouse API step 1: sol.input and pressed/released events

Remove "inside the viewport" here and "relative to the viewport" below. Everything else in the API is obviously relative to the quest screen, indepedently of black bars, window decoration, etc.

For example, sol.main:on_draw() draws on the quest screen. There is no unnecessary notion of viewport that makes the documention more complex.

Saying "quest size coordinates" already gives accurate information. Thanks