This is a second revision of the patch to add MI command that
creates varobjs for registers. The command is renamed to -var-list
and used like:

	-var-list --registers

There are now docs and tests. The created variable objects no longer
have 'public' pseudo-fields, no matter what the language of the program is.

Along the way, I've promoted a private function in ada-lang.c to language.c,
so I'd appreciate if Ada maintainers take a quick look.

OK?

- Volodya

	Implement the -var-list command, with initial support
	for listing registers.
	* mi/mi-cmds.h (mi_cmd_var_list): New.
	* mi/mi-cmds.c: Register "var-list".
	* mi/mi-cmd-var.c (create_varobj_in_frame): New function.
	(mi_cmd_var_create): Use the above.
	(restore_language_mode): New.
	(mi_cmd_var_list): New.
	* language.h (restore_language): Declare.
	* language.c (restore_language): New function.
	* ada-lang.c (restore_language): Remove.
	(lookup_symbol_in_language): Adjust.
	* Makefile (mi-cmd-var.o): Update dependencies.

	doc/
	* gdb.texinfo (GDB/MI Variable Objects): Document
	-var-list.

	testsuite/
	* gdb.mi/mi-var-cmd.exp: Test for -var-list.