Fixed measurement widget bug.

For some reason, the measurement widget unit dropdown menu would not
function properly if tabindex="-1" was used on the modal.
Also added a loading.gif to the print modal.
Fixed print error

Had a user getting error "TypeError: Cannot set property 'onload' of
undefined".
Believe it has something to do with my use of childWindow.onload.  Now
just using window.open instead.
Added loading.gif to print modal.