[krbdev.mit.edu #4172] improvements to netidmgr dialogs

[Jeffrey Altman via RT]

The NSIS installer will need to be updated in the future.  It is more
important to get the code changes in for the application at this time.

These changes should be pulled up to 1.4.4 and 1.5.1.  1.4.4 because the
final KFW 3.1 release will eventually be made off of that release.

Please update the value of src/windows/winlevel.h on the 1.4 and 1.5
branches