Call local utility to reset nagging timers

This will ensure nagging is predictable during session: on first
opportunity (which is normally new terminal window) `tasknag` will nag
about everything, then according to preset intervals.

dotfiles/i3/config

 exec "hexchat --minimize=2"
 exec "nm-applet"
 exec "shutter --min_at_startup"
+exec "tasknag -R"