Some more bugfixes.

* Updates to the plot from SDF-editor help page
* Makes the tool-tip image size scale according to the chart view
* Changes the standard XY-plot title to "y against x"
* Makes the rendering of molecule images in the tool-tip and 2D-view work even if the SD-file dont have 2D-coords
Merge pull request #42 from KlasJoenssson/Debuging

Some more bugfixes.