stub help modal; cleanup

src/keys/help.rs

@@ -0,0 +1,13 @@
+use crate::*;
+
+impl Taggart {
+    pub fn handle_help (&mut self, event: &Event, _page: u8) {
+        match event {
+            press!(Esc) => { self.mode = None },
+            _ => {}
+        }
+    }
+    pub fn help_begin (&mut self) {
+        self.mode = Some(Mode::Help { page: 0 })
+    }
+}