Revert "nemo-desktop: use app_id as .desktop file name (linuxmint#3340)"

This reverts commit 4aa7a7b.

The easiest way to find the desktop file for Nemo is to call it
nemo.desktop.

Not any of the following:

org.Nemo
com.Nemo
io.Nemo
com.cinnamon.Nemo
com.linuxmint.cinnamon.Nemo

This creates regressions since it breaks any ref to the app (namely
people adding it as a pin in GWL) and it serves no purpose nor fixes
any bugs we're aware of.

Revert "nemo-desktop: use app_id as .desktop file name (linuxmint#3340)"

This reverts commit 4aa7a7b.

The easiest way to find the desktop file for Nemo is to call it
nemo.desktop.

Not any of the following:

org.Nemo
com.Nemo
io.Nemo
com.cinnamon.Nemo
com.linuxmint.cinnamon.Nemo

This creates regressions since it breaks any ref to the app (namely
people adding it as a pin in GWL) and it serves no purpose nor fixes
any bugs we're aware of.

org.nemo.root.policy.in: Allow escalation for remote users.

ref: linuxmint/linuxmint#629

nemo-list-view.c: Don't apply column-expand test unless there is

a drag operation active.

This test also affects clicking on the expander.