Hay! Look! Actual fancy stuff! Shove
Include Shove/Shove.event somewhere in free space in your buildfile (if you are not using buildfiles, then please do).
You will need all the other files and folder too, so be careful.
This version is simple as it allows every non-mounted units to shove any other non-mounted units.
Also, the Shove command is yellow and has priority over any other command. But you can simply change that by changing the command order (and color parameter) in the Shove/Shove.event file.
Skill System version 
Now also included in circles’ Skill System.