Acknowledge Tom Lord as author of gdba.el.

Acknowledge Tom Lord as author of gdba.el.
Use let construction to bind buffer-read-only to nil.
(gdba): 'set height 0' in GDB.
(gdb-display-end, gdb-frame-handler): Corrections to forming
full expression name for header-line in display frame.
(gdb-info-breakpoints-custom): Highlight breakpoints since
they may be clicked on with mouse-2.
(gdb-quit): Delete frames of displayed expressions when
quitting.
(gdb-delete-frames): New function.
(gdb-source-info): Don't create stack buffer automatically.