New features

Warp mouse near the screen edge, emulating displays to the left or
right. This is similar to the
https://github.com/mogenson/WarpMouse.spoon approach. (#178)
Saving & restoring of window state into a temporary file. This
should make it less tedious to restart the window manager and
having to reshuffle all the windows.
Nix-darwin module (#177)

Notable Fixes

Scrolling layout strips no longer causes inadvertant scrolling
inside of the application windows. (#101)
Edge cases where a lost focus event would cause all window
operations requiring a currently focused window to become
unresponsive.
When starting Paneru would gather all the windows from all
displays on the current display. This has now been fixed and the
windows remain where they are.
Windows on separate displays would no longer be auto-dimmed. This
allows watching YouTube on another display without the dimming
effect.
Configuration file detection in XDG_CONFIG_HOME is now more robust.
Some endgecases with window sizing should be fixed. (#168)

Full Changelog: v0.4.0...v0.4.1