* Refactor edit one field dialogs to use validators and transfer data to and
from window functions.
* Add code to DIALOG_SHIM to handle validation and transfer functions since
the base dialog class code is not called by EndQuasiModal().
* Add custom validator class for filtering field text control characters.
* Add new field validator to edit schematic component dialog field text
control.
* Add new field validator to edit fields in library editor dialog field
text control.
* Make a few LIB_PART member functions const.
Wayne Stambaugh