Backporting r14305 to fix <controlfield> creation and use (when missing) bug:

Backporting r14305 to fix <controlfield> creation and use (when missing) bug:

When we add a <controlfield> element we need to set it to be 40 characters
long, and full of spaces, otherwise the Fixed Field editor cannot properly
set the positions.

Additionally, when a Fixed Field is edited but there is no backing
<controlfield> element (say, trying to set the Audn when there is no 008)
then we will add the needed <controlfield>.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_1_6_0@14311 dcc99617-32d9-48b4-a31d-7c20da2025e4