Add check_matching_dims for std::vector<eigen<var>>

[rok-cesnovar]

Summary

Fixes #2207

Mainly fixes this case:

std::vector<Eigen::Matrix<double, -1, 1>> z_1_offset;
std::vector<Eigen::Matrix<stan::math::var, -1, 1>> z_1;
size_t M_1 = 5;
size_t N_1 = 4;
z_1_offset = std::vector<Eigen::Matrix<double, -1, 1>>(M_1, Eigen::Matrix<double, -1, 1>(N_1));
z_1 = std::vector<Eigen::Matrix<stan::math::var, -1, 1>>(M_1, Eigen::Matrix<stan::math::var, -1, 1>(N_1));

check_matching_dims("constraint", "z_1", z_1, "offset", z_1_offset);

Tests

Added test for the case that caused the issue and a few others.

Side Effects

/

Release notes

Fixed a bug in check_matching_dims that prevented checking vectors of Eigen matrices of vars.

Checklist

• Math issue #(issue number)

• Copyright holder: (fill in copyright holder information)

  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

[rok-cesnovar]

The original bug in the is_rev_matrix template metaprogram was fixed in one of the varmat PRs. This PR now just fixes an ambiguity for the all-scalar case and adds tests so we dont reintroduce the original bug again.

[rok-cesnovar]

The tests now pass so this is ready for review. Also checked that the problematic model @wds15 posted in the original issue compiles.

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.44	3.36	1.02	2.21% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	0.98	-2.54% slower
eight_schools/eight_schools.stan	0.11	0.12	0.92	-9.28% slower
gp_regr/gp_regr.stan	0.15	0.16	0.98	-1.86% slower
irt_2pl/irt_2pl.stan	5.11	5.24	0.98	-2.55% slower
performance.compilation	92.4	89.67	1.03	2.96% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.65	8.67	1.0	-0.21% slower
pkpd/one_comp_mm_elim_abs.stan	30.3	28.81	1.05	4.92% faster
sir/sir.stan	136.99	135.68	1.01	0.96% faster
gp_regr/gen_gp_data.stan	0.04	0.04	1.02	1.92% faster
low_dim_gauss_mix/low_dim_gauss_mix.stan	3.07	3.05	1.01	0.84% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.39	0.39	1.0	0.28% faster
arK/arK.stan	2.54	2.56	0.99	-0.76% slower
arma/arma.stan	0.62	0.62	0.99	-0.85% slower
garch/garch.stan	0.57	0.58	0.98	-2.06% slower
Mean result: 0.996952532213

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Jenkins Console Log
Blue Ocean
Commit hash: 566e1b2

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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