Optimize images (#464)

Recompress losslessly using `optipng` and `advpng`
2019-06-27 21:33:11 +02:00
--- a/mesecons_receiver/textures/receiver_bottom_off.png
+++ b/mesecons_receiver/textures/receiver_bottom_off.png
--- a/mesecons_receiver/textures/receiver_bottom_on.png
+++ b/mesecons_receiver/textures/receiver_bottom_on.png
--- a/mesecons_receiver/textures/receiver_fb_off.png
+++ b/mesecons_receiver/textures/receiver_fb_off.png
--- a/mesecons_receiver/textures/receiver_fb_on.png
+++ b/mesecons_receiver/textures/receiver_fb_on.png
--- a/mesecons_receiver/textures/receiver_lr_off.png
+++ b/mesecons_receiver/textures/receiver_lr_off.png
--- a/mesecons_receiver/textures/receiver_lr_on.png
+++ b/mesecons_receiver/textures/receiver_lr_on.png
--- a/mesecons_receiver/textures/receiver_top_off.png
+++ b/mesecons_receiver/textures/receiver_top_off.png
--- a/mesecons_receiver/textures/receiver_top_on.png
+++ b/mesecons_receiver/textures/receiver_top_on.png