Begin work on --bg tests

Makefile

README

test/bg.png

test/bg_451x500.png

test/bg_451x500_center.png

test/bg_451x500_fill.png

test/bg_451x500_max.png

test/bg_451x500_scale.png

test/bg_451x500_tile.png

test/bg_500x333.png

test/bg_500x333_center.png

test/bg_500x333_fill.png

test/bg_500x333_max.png

test/bg_500x333_scale.png

test/bg_500x333_tile.png

test/bg_all.png

test/feh-bg.i

test/run-bg