test/random/rng: made stats print stddev / range;¹ reduced output.

1: Makes ratio for full signed distributions uniform with unsigned
distributions.
gfx/display: added width() and height() queries.
input: added display_resize event, implemented event for GLFW & SDL.
input: corrected MouseButtonEvent action member name.
input_buffer: added event data test logging.
test/gfx/display: made display resizable.