v3.5.1 - minor update to make bond order enums available when setting the order of pre-exisitng bonds

v3.5.0 - update to RCDKlibs 2.3. This changes uderlying AtomContainer defualt to Atomcontainer2 and also has new support for mass spec mass functions. On the rcdk side we have moved to a tidyverse documentation and build system.

v3.4.7 - minor update to comply with CRAN policy. Minimum Java 8 required; fix an issue where unittests were writing to system files.

v3.3.5 - update to work with CDK 1.5.13 with the new Depiction module

v2.9 - Updated to the new package structure where the CDK libs are removed.
As a result, this package now depends on the rcdklibs package

v2.8.1 - Fixed typos in the docs

v2.8 - Updated code to provide accessors for atoms and bonds of a molecule. 
Also provide methods to access atom and bond properties. Currently, setters
for these objects are not provided

v2.7 - Removed support for JChemPaint due to it being in flux at this point. Also 
removed support for viewing tables of 3D structures. Restructured the descriptor
functions to utilize descriptor names and i general make descriptor calculations
more R-like
