Plugins: Eliminate 'Loading' splash unless disk is inactive
My impression is that the waiting time for plugins
is only ever significant if a disk needs to spin up.
In other cases, the experience seems nicer
without a 'Loading' splash, especially for
often-used plugins, such as 'Properties',
when it is launched from the Database or
from the File Browser.
Change-Id: I018ccb13466fa618ef089b6dc7714db38cffd9b6