(gdb-delete-display): Rename (gdb-delete-expression).

(gdb-delete-display): Rename (gdb-delete-expression).
(gdb-goto-bp-this-line): Rename (gdb-goto-breakpoint).
(gdb-toggle-bp-this-line): Rename (gdb-toggle-breakpoint).
(gdb-delete-bp-this-line): Rename (gdb-delete-breakpoint).
(gdb-toggle-disp-this-line): Rename (gdb-toggle-display).
(gdb-delete-disp-this-line): Rename (gdb-delete-display).
(gud-gdba-marker-filter): Remove unnecessary save-match-data.
(gdb-mouse-goto-breakpoint, gdb-frames-select): New functions.
(gdb-frames-mouse-select): Simplify.
Make keybindings (gdb-goto-breakpoint, gdb-frames-select, etc)
consistent with other modes in emacs.
(gdb-display-source-buffer): Return window of source buffer
for (gud-display-line).