Qt5 followup

Created output paths are then consistent with Linux / macOS.
Switched from deprecated CMake variables to newer ones.

Migrate to Qt5

- Works on Mac
- Needs to be checked on Linux / Windows.

- Required lib version can be in a range
- conan build ../path/to/source builds with conan specified compiler

Cleanup output messages

The time for the linear solver is written already in NonLinearSolver::solver().