v4.2a1

Major changes

Since v4.2a0:

• More rendering improvements in discrete
• Improvements to DecisionTree code to support hybrid branch
• Deprecated (old) Lie{Scalar|Vector|Matrix} classes
• Moved many deprecated functions inside ifdefs

List of PRs

• Two small fixes by @dellaert in #996
• Force nonnegative scale for Sim(3) by @johnwlambert in #997
• Moved empty to Factor base class. by @dellaert in #998
• Fix documentation on ProjectionFactorPPPC by @dwisth in #1004
• Minor changes to LocalPlaneFactor by @dwisth in #1003
• DecisionTree Improvements by @varunagrawal in #1002
• Spring cleaning: deprecate -> 4.2 by @dellaert in #999
• DecisionTree refactor by @dellaert in #1000
• render values in markdown by @dellaert in #1001
• More DecisionTree improvements by @dellaert in #1005

Full Changelog Since 4.1.1: 4.1.1...4.2a1