bumped version to 1.6.0

bumped version to 1.5.0

Fixed compile errors that occurred in Unity 2021.2 and newer.

Fixed that ExitGUIException caused the PlayMode Inspector window to display "An error occurred" until the GameObject selection was changed.
Bumped package version to 1.4.0

bumped version to 1.3.0

bumped version to 1.2.0

bumped version to 1.1.0

first drop