Bumped Sundials library to v4.

[pbtoast]

Made several code changes to solvers. INK ARK solver is no longer supported at the moment.

[codecov[bot]]

Codecov Report

Merging #341 into master will decrease coverage by 0.03%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #341      +/-   ##
==========================================
- Coverage   80.67%   80.63%   -0.04%     
==========================================
  Files         244      243       -1     
  Lines       38211    37918     -293     
==========================================
- Hits        30825    30575     -250     
+ Misses       7386     7343      -43

Impacted Files	Coverage Δ
solvers/ark_ode_solver.c	50.32% <0%> (-11.51%)	:arrow_down:
solvers/krylov_solver.c	73.37% <0%> (-0.16%)	:arrow_down:
solvers/dense_newton_solver.c	89.16% <0%> (ø)	:arrow_up:
solvers/am_ode_solver.c	0% <0%> (ø)	:arrow_up:
solvers/newton_solver.c	60% <0%> (ø)	:arrow_up:
solvers/dae_solver.c	65.06% <0%> (ø)	:arrow_up:
solvers/tests/test_ink_ark_ode_solver.c
solvers/bdf_ode_solver.c	65.09% <0%> (+0.24%)	:arrow_up:
solvers/tests/diurnal_solver.c	97.06% <0%> (+0.55%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 9dc06da...b623ec3. Read the comment docs.

[codecov[bot]]

Codecov Report

Merging #341 into master will decrease coverage by 0.03%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #341      +/-   ##
==========================================
- Coverage   80.67%   80.63%   -0.04%     
==========================================
  Files         244      243       -1     
  Lines       38211    37926     -285     
==========================================
- Hits        30825    30581     -244     
+ Misses       7386     7345      -41

Impacted Files	Coverage Δ
solvers/ark_ode_solver.c	50.64% <0%> (-11.19%)	:arrow_down:
solvers/krylov_solver.c	73.37% <0%> (-0.16%)	:arrow_down:
solvers/dense_newton_solver.c	89.16% <0%> (ø)	:arrow_up:
solvers/am_ode_solver.c	0% <0%> (ø)	:arrow_up:
solvers/newton_solver.c	60% <0%> (ø)	:arrow_up:
solvers/dae_solver.c	65.06% <0%> (ø)	:arrow_up:
solvers/tests/test_ink_ark_ode_solver.c
solvers/bdf_ode_solver.c	65.21% <0%> (+0.36%)	:arrow_up:
solvers/tests/diurnal_solver.c	97.06% <0%> (+0.55%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 9dc06da...b623ec3. Read the comment docs.