mmv pmda - add mmv.debug
mmv pmda - add mmv.debug

Add the metric, store support so it can be set on the fly, help text.
Also added some initial diagnostics to help with debugging.

edwardt/pcp,andyvand/cygpcpfans,wuliming/pcp,mbaldessari/pcp,mbaldessari/pcp,edwardt/pcp,tjanez/pcp,edwardt/pcp,ryandoyle/pcp_original,prasincs/pcp,aeg-aeg/pcpfans,ryandoyle/pcp_original,prasincs/pcp,edwardt/pcp,wuliming/pcp,wuliming/pcp,andyvand/cygpcpfans,edwardt/pcp,aeg-aeg/pcpfans,mbaldessari/pcp,prasincs/pcp,adfernandes/pcp,aeg-aeg/pcpfans,prasincs/pcp,wuliming/pcp,wuliming/pcp,tjanez/pcp,adfernandes/pcp,andyvand/cygpcpfans,wuliming/pcp,andyvand/cygpcpfans,adfernandes/pcp,ryandoyle/pcp_original,prasincs/pcp,adfernandes/pcp,tjanez/pcp,wuliming/pcp,aeg-aeg/pcpfans,andyvand/cygpcpfans,edwardt/pcp,tjanez/pcp,wuliming/pcp,prasincs/pcp,ryandoyle/pcp_original,mbaldessari/pcp,mbaldessari/pcp,tjanez/pcp,edwardt/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,ryandoyle/pcp_original,adfernandes/pcp,aeg-aeg/pcpfans,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,tjanez/pcp,ryandoyle/pcp_original,prasincs/pcp,tjanez/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,edwardt/pcp,mbaldessari/pcp,tjanez/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,ryandoyle/pcp_original,ryandoyle/pcp_original,prasincs/pcp