Fix for dbl bond stereo in 2d layout
Previously dbl bond stereo was corrected after the everything else was laid out. This caused clashes. Now it's laid out after the initial layout and before the systematic layout. This should also give a small speed up (dbl bonds with stereo are not subject to the systematic layout)
Merge pull request #40 from baoilleach/depictionCTstereo

Fix for dbl bond stereo in 2d layout