Fixed extents to respect direction of axes.
Moved main into form so new devs have only one entry-point to start.
Moved extents methods to extension methods on their respective classes
  but with facades on the Chart class for easy access.
Implemented extents for second X/Y axes if present (no demo though).
Added GUI demos for extents and plotting with reversed axes.
Merge pull request #10 from pckujawa/axisDirectionAwareness

Fixed extents to respect direction of axes; more granular extents methods; misc