Removed the $:: notation from a lot of global variables; this is needed to

Removed the $:: notation from a lot of global variables; this is needed to
get "use strict" to do something useful regarding these global variables.
Because of this change, a number of accessor functions have been created to
let installer.pl get/set some of these global variables. (We should not use
the $Install:: notation for the global variables either, as that will also
make "use strict" do nothing about these variables.)

POD updates