VMMakerTool change '64 bit VM?' selection box label and balloon help

 
The '64 bit VM?' selection box in VMMakerTool can be confusing for first-time
VM builders. See for example:
   http://lists.squeakfoundation.org/pipermail/squeak-dev/2009-August/138006.html.

For this reason I have changed the label on the selection box from '64 bit VM?'
to '64-bit word', and the balloon help from 'Set to build a 32 bit VM or a
64 bit VM' to 'Build (32- or 64-bit) VM to run 64-bit images. Default is false
to support normal 32-bit images.'.

The change is in VMMaker-dtl.129 on SqueakSource, and will be in effect for newly
opened VMMakerTool windows.

Dave