PR gdb/15830

PR gdb/15830

gdb/ChangeLog:

	PR gdb/15830
	* NEWS: The "maint demangle" command is renamed as "demangle".
	* demangle.c: #include cli/cli-utils.h, language.h.
	(demangle_command): New function.
	(_initialize_demangle): Add new command "demangle".
	* maint.c (maintenance_demangle): Stub out.
	(_initialize_maint_cmds): Update help text for "maint demangle",
	and mark as deprecated.

gdb/doc/ChangeLog:

	* gdb.texinfo (Debugging C Plus Plus): Mention "demangle".
	(Symbols): Ditto.
	(Maintenance Commands): Delete docs for "maint demangle".

gdb/testsuite/ChangeLog:

	* gdb.base/maint.exp: Remove references to "maint demangle".
	* gdb.cp/demangle.exp: Update.  "maint demangle" -> "demangle".
	Add tests for explicitly specifying language to demangle.
	* gdb.dlang/demangle.exp: Ditto.