Plugin Version 3.0

Update Readme to Plugin Version 3

Plugin Version 1.1

Easier adoption for new themers:
Move most of the changes a themer has to make from android manifest to strings.xml
Split the Layers_OverlayNames into NormalOverlaynames and StyleSpecificoverlayNames
New recommended screenshot height: 750px (to prevent the layers Manager app from crashing on Low Memory devices)
A new documentation on how to make a Plugin Overlay