Standardise debug variables

This makes all debug options stored in a single struct rather than in
various places, changes/fixes the behaviour of existing options, and
introduces some new options.

* Fixes damage issues with `-Drender-tree` texture (by removing scissor)
* Offsets the render tree overlay's `y` position for those who have
swaybar at the top
* Replaces `-Ddamage=rerender` with `-Dnodamage`
* Replaces `-Ddamage=highlight` with `-Dhighlight-damage`
* Replaces `-Dtxn-debug` with `-Dtxn-wait`
* Introduces `-Dnoatomic`
* Removes the `create_time` and `ms_arranging` figures from transactions
and the log message. Transactions are created after arranging and the
create time is of no significance.
* Fixes `-Dtxn-debug` (now `-Dtxn-wait`) not working.

include/sway/debug.h

@@ -1,15 +1,18 @@
 #ifndef SWAY_DEBUG_H
 #define SWAY_DEBUG_H
+#include <stdbool.h>
+
+struct sway_debug {
+	bool highlight_damage; // Highlight regions of the screen being damaged
+	bool noatomic;         // Ignore atomic layout updates
+	bool nodamage;         // Render the full output on each frame
+	bool render_tree;      // Render the tree overlay
+	bool txn_timings;      // Log verbose messages about transactions
+	bool txn_wait;         // Always wait for the timeout before applying
+};
+
+extern struct sway_debug debug;
 
-// Tree
-extern bool enable_debug_tree;
 void update_debug_tree();
 
-// Damage
-extern const char *damage_debug;
-
-// Transactions
-extern int txn_timeout_ms;
-extern bool txn_debug;
-
 #endif

include/sway/server.h

@@ -54,8 +54,7 @@ struct sway_server {
 	struct wl_listener server_decoration;
 	struct wl_list decorations; // sway_server_decoration::link
 
-	bool debug_txn_timings;
-
+	size_t txn_timeout_ms;
 	list_t *transactions;
 	list_t *dirty_containers;
 };