admin: add manual "Send Password reset" to accounts tab

Only appears with Reset links enabled.
Pressing this sends a PWR link to the users selected.
if one user is selected, or if one of you selected users doesn't have a
method of contact, a link is given to the admin to send to them
manually.

main.go

@@ -108,6 +108,7 @@ type appContext struct {
 	newUpdate        bool // Whether whatever's in update is new.
 	tag              Tag
 	update           Update
+	internalPWRs     map[string]InternalPWR
 }
 
 func generateSecret(length int) (string, error) {