Log Message:
taisei: Update to 1.3.1

This is a stable maintenance release. It features some important bugfixes and a \ 
few optimizations and visual improvements backported from the v1.4 development \ 
tree, as well as new character art by @afensorm.

Other than fixing some rare game-breaking bugs, there are no gameplay changes \ 
and this version should be replay-compatible with the initial v1.3 release.