Resolve "Segmentation fault in FromFile due to RASTER=TRUE"

Closes #465

See merge request !275

get all combinations in case of RASTER=TRUE.

Resolve "Make `src/Classic/Solvers/GreenWakeFunction::testApply()` a unit test"

Closes #455

See merge request !272

Resolve "cleanup: make Classic compile with -Wextra and -Werror"

Closes #454

See merge request !269

Port IPPL simple unit tests to OPAL unit tests and cleanup

See merge request !270

Add FFT/SeaborgRes applications to CMake

See merge request !271

Resolve "cleanup: make optimizer compile with -Wextra and -Werror"

Closes #453

See merge request !268

Resolve "cleanup: make IPPL compile with -Wextra and -Werror"

Closes #452

See merge request !266

Merge branch '452-cleanup-make-ippl-compile-with-wextra-and-werror' of gitlab.psi.ch:OPAL/src into 452-cleanup-make-ippl-compile-with-wextra-and-werror

Resolve "Unused classes in OPAL"

Closes #451

See merge request !265

Resolve "cleanup: remove outdated IPPL documentation"

Closes #450

See merge request !263

Resolve "Review ippl/test directory"

See merge request !264

Resolve "get rid of linker warning on macOS with clang"

Closes #449

See merge request !262

Resolve "cleanup: UNDEFINED macro in ippl"

Closes #448

See merge request !261

Resolve "cleanup: remove OLD_SWAP_PARTICLES"

Closes #446

See merge request !259

cleanup and fix compilation of ippl/test applications

See merge request !260