It has been a while since the last optipng run (it was in 2015),
and many non-optimized PNG files have accumulated in the repository.
288 of 1666 files optimized, 258992 bytes reduced to 156258 bytes; -102734 bytes, -39.66%
To avoid unnecessarily increasing the size of Git repository for minor
size reductions, we skip images that weren't reduced by at least 15%.
Overall statistics (only for files with a smaller recompressed size):
Original size: 16720 KiB on 404 files
Optimized size: 15237 KiB
Total saving: 1482 KiB = 8% decrease
This commit is a follow-up of 82b8d9ecdf
The updated 16x16 terrain type icons need to be wired with the 16x16 TC-able icon base so that the status info works properly.
30x30 icons are provided for a future use in high-res displays, where they should be overlaid on top of the 32x32 TC-able icon base
Overall statistics (only for files with a smaller recompressed size):
Original size: 105 KiB on 167 files
Optimized size: 66 KiB
Total saving: 38 KiB = 36% decrease
Overall statistics (only for files with a smaller recompressed size):
Original size: 423 KiB on 192 files
Optimized size: 216 KiB
Total saving: 207 KiB = 48% decrease
