set verbositylevel command

[Fyles, Matthew]

In the source ui-out.c there is a function ui_out_get_verblvl(struct
ui_out *uiout) which if implemented would appear to allow the user
disable all command language output.

This would be a really useful feature for me to use.

Has somebody already release a patch for this or is the work still
pending.

I notice from the GDB 5.3 source that the code still has "FIXME: not
implemented yet" so should I implement it myself using the existing
framework?