bootstrap:common: STATIT framework
bootstrap:types: statit_typs: compute stats over typ instances
bootstrap:types; fix use of magic number instead of its define
bootstrap:typs: add_user: fix egregious case of over-registration

Some calls to add_user() are superfluous, add_user() is supposed to
ignore them. But the logic was letting through many cases. The stats on
an empty NCC_EXAMPLE before:

	statit_typs
		17456   total_users
		0.333   total_users/count
		1160    max_users

After:

	statit_typs
		11407   total_users
		0.218   total_users/count
		9       max_users