Adds vectorized versions of the constrain functions

[SteveBronder]

Summary

Adds vectorized versions of the constrain functions that can take in containers of containers. This uses the same pattern as #2578 's *_free functions but with the *_constrain functions

Tests

Tests were added to check that going from untransformed -> constrained -> free'd of containers gives back the original values. Tests can be run with

./runTests.py -j4 test/unit/math/prim/fun/cholesky_corr_transform_test.cpp \
test/unit/math/prim/fun/cholesky_factor_transform_test.cpp \
test/unit/math/prim/fun/corr_matrix_transform_test.cpp \
test/unit/math/prim/fun/cov_matrix_transform_test.cpp \
test/unit/math/prim/fun/ordered_transform_test.cpp \
test/unit/math/prim/fun/positive_ordered_transform_test.cpp \
test/unit/math/prim/fun/simplex_transform_test.cpp \
test/unit/math/prim/fun/unit_vector_transform_test.cpp

Side Effects

Nope!

Release notes

Adds vectorized versions of the *_constrain functions

Checklist

• Math issue #(issue number)

• Copyright holder: Steve Bronder

  The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the license the submitted work under the following licenses:
  - Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
  - Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

• the basic tests are passing

  • unit tests pass (to run, use: ./runTests.py test/unit)
  • header checks pass, (make test-headers)
  • dependencies checks pass, (make test-math-dependencies)
  • docs build, (make doxygen)
  • code passes the built in C++ standards checks (make cpplint)

• the code is written in idiomatic C++ and changes are documented in the doxygen

• the new changes are tested

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.41	3.46	0.99	-1.27% slower
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	0.99	-1.09% slower
eight_schools/eight_schools.stan	0.09	0.1	0.97	-2.94% slower
gp_regr/gp_regr.stan	0.14	0.14	0.99	-1.02% slower
irt_2pl/irt_2pl.stan	5.07	5.1	0.99	-0.61% slower
performance.compilation	91.49	88.99	1.03	2.74% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.15	8.19	0.99	-0.55% slower
pkpd/one_comp_mm_elim_abs.stan	31.11	30.0	1.04	3.56% faster
sir/sir.stan	118.8	122.99	0.97	-3.53% slower
gp_regr/gen_gp_data.stan	0.03	0.03	0.99	-0.54% slower
low_dim_gauss_mix/low_dim_gauss_mix.stan	3.03	3.03	1.0	0.07% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.37	0.4	0.94	-6.29% slower
arK/arK.stan	2.07	2.07	1.0	-0.25% slower
arma/arma.stan	0.25	0.25	0.99	-0.63% slower
garch/garch.stan	0.61	0.61	1.0	-0.02% slower
Mean result: 0.992314499557

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Jenkins Console Log
Blue Ocean
Commit hash: 1b909ee

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Machine information

ProductName: Mac OS X ProductVersion: 10.11.6 BuildVersion: 15G22010

CPU:
Intel(R) Xeon(R) CPU E5-1680 v2 @ 3.00GHz

G++:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

Clang:
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

[bob-carpenter]

Beautiful. Thanks!