Added some signals & slots, so that the QnetTool displays are updated properly...

Added some signals & slots, so that the QnetTool displays are updated properly when setting apriori values.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@2393 41f8697f-d340-4b68-9986-7bafba869bb8