* Made the whole block a separated scene to demonstrate it can work across multiple instances.
* Dropped the Area.input_event and did everything manually with raycasting.
* Made quad_mesh_size automatically pick the quad size, avoiding the extra setup.
* Changed from PlaneMesh to QuadMesh. Now everyting can start with 0 rotation.
* The function will keep handling input when the mouse is outside of the area to avoid orphan clicks, but stop when the click is released.
* Changed some variable and function names to make sense with the code changes.
* Added an extra function to deal with billboard mode. But is not perfect, specially with scaling and Y-billboard + camera tilting.
The scripts were streamlined using more or less the following conventions:
- space after a comma in lists of arguments
- space around weak operators (+, -), no space around strong operators (*, /)
- space after a comment start (#)
- removed trailing spaces or tabs, apart from those that delimit the function indentation level (those could be removed too but since they are added automatically by the editor when typing code, keeping them for now)
- function blocks separate by two newlines
The scene files were resaved with the (current) 2.0 format, and some scenes that were in XML format were converted to SCN, to be consistent across all demos.
