columns: switch to bitflag app options

we're adding a ScrollToTop bool for an updating change
to the toolbar, but we have too many flags now. Let's switch
to bitflags

Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck_columns/src/options.rs

@@ -0,0 +1,26 @@
+use bitflags::bitflags;
+
+bitflags! {
+    // Attributes can be applied to flags types
+    #[repr(transparent)]
+    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct AppOptions: u64 {
+        /// Explicitly enable/disable column persistence for the sessions
+        const TmpColumns    = 1 << 0;
+
+        /// Debug mode for debug ui controls
+        const Debug         = 1 << 1;
+
+        /// Should we explicitly disable since optimization?
+        const SinceOptimize = 1 << 2;
+
+        /// Should we scroll to top on the active column?
+        const ScrollToTop   = 1 << 3;
+    }
+}
+
+impl Default for AppOptions {
+    fn default() -> AppOptions {
+        AppOptions::SinceOptimize
+    }
+}