Release 4.2a9

This is hopefully the last 4.2 pre-release. I had planned to cut 4.2 this weekend but there were still apparently some issues with the wrapper when used in Georgia tech's CS 3630 course (325 students using GTSAM) and so I'd rather wait another week for these things to settle down. In the meantime, though, we needed a pre-release so %pip install gtbook works on Google Colab and installs 4.2a9 in the process. All works now, as evidenced at roboticsbook.org.

The biggest changes are:

• moved away from boost utilities to c++ initializers in all tests and examples.
• a cleaned up and correctly working hybrid inference framework. Thanks @varunagrawal and @ProfFan !
• template-magical NoiseModelFactorN which allows an arbitrary number of variables connected to factors. Thanks @gchenfc !
• several important bug-fixes and edits, by many new contributors, listed below:

New Contributors

• @nkhedekar made their first contribution in #1330
• @MigVega made their first contribution in #1331
• @ulterzlw made their first contribution in #1340
• @jrpowers made their first contribution in #1361
• @stefangachter made their first contribution in #1296
• @njayakumar3 made their first contribution in #789
• @BrettRD made their first contribution in #1376
• @acowley made their first contribution in #1381

Detailed Changes

• Add an expression for normalize() by @nkhedekar in #1330
• Update README.md by @MigVega in #1331
• Hybrid Elimination by @varunagrawal in #1339
• Fixed Jacobian in python CustomFactorExample by @ulterzlw in #1340
• Hybrid Mixture Error by @varunagrawal in #1318
• Hybrid Multifrontal by @varunagrawal in #1323
• NoiseModelFactorN - fixed-number of variables >6 by @gchenfc in #947
• GaussianConditional logDeterminant by @varunagrawal in #1345
• Replace NoiseModelFactor1 in with NoiseModelFactorN in pre-made factors by @gchenfc in #1344
• Hybrid Bayes Net sampling by @varunagrawal in #1347
• Fix wrapper warnings by @varunagrawal in #1348
• Update geometry.i : wrap multiplication of Rot3 and Unit3 by @akshay-krishnan in #1302
• Sampling test for Hybrid Posterior by @varunagrawal in #1346
• Some refactoring and new test by @dellaert in #1349
• Add logDensity and evaluate to GaussianBN and HybridBN by @dellaert in #1352
• Added convenience constructors and python wrappers by @dellaert in #1353
• Wrap constructors for PreintegratedAhrsMeasurements by @varunagrawal in #1354
• HybridValues specify continuous then discrete by @varunagrawal in #1355
• Likelihoods and other improvements by @dellaert in #1356
• Proper Hybrid Elimination by @varunagrawal in #1319
• Test on ratio by @dellaert in #1357
• Hybrid Improvements by @varunagrawal in #1343
• Fix HybridGaussianFactorGraph error by @varunagrawal in #1358
• Initializer list and insert/update chaining by @dellaert in #1359
• Slightly expand Python API by @jrpowers in #1361
• Check for native architecture and set GTSAM_COMPILE_OPTIONS_PUBLIC accordingly by @stefangachter in #1296
• Fix hybrid tests by @varunagrawal in #1363
• Fixed a few small issues... by @dellaert in #1367
• Switch to EliminateDiscrete for max-product by @dellaert in #1362
• Hybrid Serialization by @varunagrawal in #1368
• Various fixes for Hybrid by @varunagrawal in #1369
• Hybrid Elimination with Normalization Constant by @varunagrawal in #1360
• Added *.bib file and started adding citations to README.md by @njayakumar3 in #789
• Un-deprecate NoiseModelFactor1-6 and move X1 and key1-6 shortcuts to NoiseModelFactorN by @gchenfc in #1370
• Two new tests, one with 5 modes by @dellaert in #1371
• Simplified AP for HybridBayesNet by @dellaert in #1372
• DefaultOrderingFunc in EliminationTraits by @varunagrawal in #1373
• Big Re-"Factor" of Hybrid by @dellaert in #1374
• More Expression wrappers by @BrettRD in #1376
• Get rid of boost::assign by @dellaert in #1375
• replace list_of with initializer list in TimeTBB.cpp by @kartikarcot in #1379
• Harmonized error/logProbability in entire Factor/Conditional hierarchy by @dellaert in #1380
• BatchFixedLagSmoother: add ability to limit warning debug prints by @acowley in #1381
• Test and fix all conditionals by @dellaert in #1386
• Some Hybrid Improvements by @varunagrawal in #1387
• Hybrid/simplify by @dellaert in #1388
• Correction to docs and lambdas by @varunagrawal in #1390
• Switch pruning test to probabilities. by @dellaert in #1394
• Deprecate filter by @dellaert in #1397
• Fix examples that were using filter by @dellaert in #1402
• Deprecated boost transform_iterators by @dellaert in #1407
• Iterator for 4.2 by @dellaert in #1417
• Fix (issue #1336) dangling pointer access violation. by @oicchris in #1423
• Fix version... by @dellaert in #1424
• 4.2 fixes by @varunagrawal in #1425
• Patch ros package (branch: release/4.2) by @jlblancoc in #1427
• Add missing header to fix gtbook by @dellaert in #1429

Full Changelog: 4.2a8...4.2a9