File Chooser active components need mnemonics added to them

Windows dialog boxes provide mnemonics in dialog boxes to allow direct navigation to active components. File chooser has none. Specific items on this Chooser needing mnemonicss are the:
 o Look in textfield
 o File name textfield
 o Files of Type textfield

The lables for each of the above also need to indicate which letter is the mnemonic.

The chooser for JLF needs to support, I will verify whether the Motif chooser should also provide them.