Moved the delete-still-existing-elements rule to build-groups
Moved the delete-still-existing-elements rule to build-groups

This was done so that I could make the following module for updating grouping
elements and generating associated code.

DrItanium/electron,DrItanium/electron-platform,DrItanium/neutron,DrItanium/electron-platform,DrItanium/AdventureEngine,DrItanium/electron,DrItanium/electron,DrItanium/AdventureEngine,DrItanium/electron-platform