* winsup/cinstall/res.rc: Added accelerators and improved focus order. Removed

* winsup/cinstall/res.rc: Added accelerators and improved focus order.  Removed
WS_DISABLED from "OK" buttons to accomodate default focus changes in net.cc and
source.cc.
* winsup/cinstall/net.cc (dialog_proc): If no radio button is selected, a
default is selected.
* winsup/cinstall/source.cc (dialog_proc): Ditto.
(check_if_enable_next): Removed.  No longer needed since a radio button will
always be selected.
(load_dialog): Removed call to check_if_enable_next.
(dialog_cmd): Ditto.  Also added default to switch.