Refined CreateScriptDialog

Added controls to enable curly braces on a new line and choose between
Windows (default) and Mac (original default) newline format
Add external (to Unity) binary and text asset area
Initial layout

NOTE: Scenes content (".unity files) don't work well with CMS systems -
they are an all or nothing thing. Only commit a scene when the changes
made are significant. Make a note about the scene commit (commit
separately?)