Repairing v3.0.6

Length of IIP set to zero when editing contents - fixed!

Bug detecting arrow ends fixed - Issue #68

Moved some CPU-heavy functions out of `draw`

Trying a tweak to improve performance

Fixed a couple of bugs; improved (?) double buffering

Revised architecture to use double buffering - hopefully faster! Ther…

…e may be some addiitional bugs - if so, please report

Fixed problem with C# .exe execute function

Working pretty well for Java... now need to test C# stuff!

Update README.md