Run the icons through ImageOptim

Knocks 70 KB off the total size.

Run the icons through ImageOptim
f691335e · Thomas Goyne · a7bb608a · a7bb608a · f691335e · a7bb608a
--- a/aegisub/src/bitmaps/button/about_menu_16.png
+++ b/aegisub/src/bitmaps/button/about_menu_16.png
--- a/aegisub/src/bitmaps/button/about_menu_24.png
+++ b/aegisub/src/bitmaps/button/about_menu_24.png
--- a/aegisub/src/bitmaps/button/about_menu_32.png
+++ b/aegisub/src/bitmaps/button/about_menu_32.png
--- a/aegisub/src/bitmaps/button/arrow_down_16.png
+++ b/aegisub/src/bitmaps/button/arrow_down_16.png
--- a/aegisub/src/bitmaps/button/arrow_down_24.png
+++ b/aegisub/src/bitmaps/button/arrow_down_24.png
--- a/aegisub/src/bitmaps/button/arrow_down_32.png
+++ b/aegisub/src/bitmaps/button/arrow_down_32.png
--- a/aegisub/src/bitmaps/button/arrow_down_stop_16.png
+++ b/aegisub/src/bitmaps/button/arrow_down_stop_16.png
--- a/aegisub/src/bitmaps/button/arrow_down_stop_24.png
+++ b/aegisub/src/bitmaps/button/arrow_down_stop_24.png
--- a/aegisub/src/bitmaps/button/arrow_down_stop_32.png
+++ b/aegisub/src/bitmaps/button/arrow_down_stop_32.png
--- a/aegisub/src/bitmaps/button/arrow_sort_16.png
+++ b/aegisub/src/bitmaps/button/arrow_sort_16.png
--- a/aegisub/src/bitmaps/button/arrow_sort_24.png
+++ b/aegisub/src/bitmaps/button/arrow_sort_24.png
--- a/aegisub/src/bitmaps/button/arrow_sort_32.png
+++ b/aegisub/src/bitmaps/button/arrow_sort_32.png
--- a/aegisub/src/bitmaps/button/arrow_up_16.png
+++ b/aegisub/src/bitmaps/button/arrow_up_16.png
--- a/aegisub/src/bitmaps/button/arrow_up_24.png
+++ b/aegisub/src/bitmaps/button/arrow_up_24.png
--- a/aegisub/src/bitmaps/button/arrow_up_32.png
+++ b/aegisub/src/bitmaps/button/arrow_up_32.png
--- a/aegisub/src/bitmaps/button/arrow_up_stop_16.png
+++ b/aegisub/src/bitmaps/button/arrow_up_stop_16.png
--- a/aegisub/src/bitmaps/button/arrow_up_stop_24.png
+++ b/aegisub/src/bitmaps/button/arrow_up_stop_24.png
--- a/aegisub/src/bitmaps/button/arrow_up_stop_32.png
+++ b/aegisub/src/bitmaps/button/arrow_up_stop_32.png
--- a/aegisub/src/bitmaps/button/assdraw_16.png
+++ b/aegisub/src/bitmaps/button/assdraw_16.png
--- a/aegisub/src/bitmaps/button/assdraw_32.png
+++ b/aegisub/src/bitmaps/button/assdraw_32.png