Add Lua functions to query keyboard bindings and remove individual keybinds

Add core script file that defines possibility of rebinding keyboard commands to a different key
Enable the execution of global customization scripts
Make `scene_helper.lua` a script automatically included in the ScriptScheduler

scripts/common_scripts.lua

@@ -0,0 +1,20 @@
+openspace.documentation = {
+    {
+        Name = "rebindKey",
+        Arguments = "string, string",
+        Documentation = "Rebinds all scripts from the old key (first argument) to the " ..
+        "new key (second argument)."
+    }
+}
+
+openspace.rebindKey = function(old_key, new_key)
+    local t = openspace.getKeyBinding(old_key)
+    openspace.clearKey(old_key)
+    for _, v in pairs(t) do
+        if v["Remote"] then
+            openspace.bindKey(new_key, v["Command"])
+        else
+            openspace.bindKeyLocal(new_key, v["Command"])
+        end
+    end
+end

scripts/scene_helper.lua

@@ -1,4 +1,21 @@
-mark_interesting_nodes = function(nodes)
+openspace.documentation = {
+    {
+        Name = "mark_interating_nodes",
+        Arguments = "List of nodes",
+        Documentation = "This function marks the scene graph nodes identified by name " ..
+        "as interesting, which will provide shortcut access to focus buttons and " .. 
+        "featured properties."
+    },
+    {
+        Name = "set_default_gui_sorting",
+        Arguments = "",
+        Documentation = "This function sets the default GUI sorting for the space " ..
+        "environment to increasing size, from solar system, through Milky Way, " ..
+        "Universe and finishing with other elements"
+    }
+}
+
+openspace.mark_interesting_nodes = function(nodes)
     for _, n in pairs(nodes) do
         if openspace.hasSceneGraphNode(n) then
             openspace.addTag(n, "GUI.Interesting")
@@ -6,7 +23,7 @@ mark_interesting_nodes = function(nodes)
     end
 end
 
-set_default_gui_sorting = function()
+openspace.set_default_gui_sorting = function()
     openspace.setPropertyValueSingle(
         'Global Properties.ImGUI.Main.Properties.Ordering',
         {