Rewrite Renderer API based on absolute samples

[nyanpasu64]

update_main_lines() should be supplied the trigger sample and the actual min/max samples of data being rendered (and either receive or extract the data from the wave), and we'd use the trigger and min/max samples to draw midlines and exactly position absolute debug plots (replacing view_moveport(viewport_center)).

This would also enable non-centered plots with correct midlines (at the cost of cluttering the UI even more).