Overall code re-organizing & layer renaming changes

- When renaming a layer, the line edit grabs the focus. If enter is pressed, it gets invisible. Also fixed positioning and size
- Re-organized the variables in Global, now they are less messy and randomly placed
- Layer, frame & brush textures stretch mode has been changed to Keep Aspect Centered

Scripts/TimelineSeconds.gd

@@ -10,7 +10,7 @@ var first : Vector2
 var last : Vector2
 
 # warning-ignore:unused_argument
-func _process(delta) -> void:
+func _process(delta : float) -> void:
 	update()
 
 #Code taken and modified from Godot's source code