#21 Deprecation causes build failure with latest version of SUNDIALS

[TVJensen]

In SUNDIALS, CVDENSE has been deprecated since v3.0.0, with legacy support for this call removed in the newly released v5.0.0.
This causes build failure on ArchLinux and derivatives, with failures on other distros likely to follow as they update their packages.

The call has been superceded by calls to SUNLINEARSOLVER or SUNMATRIX - see https://computing.llnl.gov/sites/default/files/public/cv_guide.pdf under release notes for 3.0.0.

The primary affected file is
fmipp-code/import/integrators/src/IntegratorStepper.cpp
line 23: Import of <cvode cvode_dense.h=""> (Header file no longer exists in 5.0.0)
line 834: Instantiation of CVDense</cvode>

• Possibly the memory management leading up to 834.

Suggested fix is to replace the call to CVDense with the superceding functions.