Extract workspace names from bindings before reordering.

fixes #1889

include/workspace.h

@@ -25,7 +25,16 @@
  */
 Con *workspace_get(const char *num, bool *created);
 
-/*
+/**
+ * Extracts workspace names from keybindings (e.g. “web” from “bindsym $mod+1
+ * workspace web”), so that when an output needs a workspace, i3 can start with
+ * the first configured one. Needs to be called before reorder_bindings() so
+ * that the config-file order is used, not the i3-internal order.
+ *
+ */
+void extract_workspace_names_from_bindings(void);
+
+/**
  * Returns a pointer to a new workspace in the given output. The workspace
  * is created attached to the tree hierarchy through the given content
  * container.