state: Connect the animation state machine to the rest

This ensures that the new state machine is fed events, as well as that its results are applied.

The old ad-hoc system is removed.

There is one regression where the last layout will be used when the panel is brought up manually.

src/main.h

@@ -0,0 +1,17 @@
+#pragma once
+/// This all wraps https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/struct.MainContext.html#method.channel
+
+#include "eek/eek-types.h"
+#include "dbus.h"
+
+struct receiver;
+struct sender;
+
+struct channel {
+    struct sender *sender;
+    struct receiver *receiver;
+};
+
+/// Creates a channel with one end inside the glib main loop
+struct channel main_loop_channel_new(void);
+void register_ui_loop_handler(struct receiver *receiver, ServerContextService *ui, DBusHandler *dbus_handler);