basic implementation of named-pipe server

doc/todo.md

@@ -16,3 +16,4 @@
     * Generalize Request across both credentials and terminal launch?
 * Make hotkey configuration a little more tolerant of slight mistiming
 * Distinguish between request that was denied and request that was canceled (e.g. due to error)
+* Use atomic types for primitive state values instead of RwLock'd types