Shape TK 1.6.1

This is the first release as part of the consolidated toolkits release.

New features

• Added functions to retrieve the version and build date of the library.

Bug fixes

• Changed to a stable sort inside OESortOverlayScores to prevent crashes with a very large number of results.
• Fixes to OEOverlap that in some cases could result in slow behavior when internal grids were rebuilt instead of being cached.
• Fix a subtle bug that could result in erroneous behavior if reusing the same OEOverlap object while changing the fit object from a grid to a molecule or from a molecule to a grid.