Update version
Merge branch 'develop' into release-0.23
Merge branch 'release-0.23' into release
Rebuild
Merge branch 'release'
Checks signal(3) availability
Style improvement
Merge branch 'configure' into feature-load-gif-animation
Merge branch 'handle-signals' into feature-load-gif-animation
Merge branch 'master' into configure
Except libsixel.pc from CLEANFILES
Merge branch 'configure' into feature-load-gif-animation