Fix SolverUtil memory issue, update testParallelSolvers, update testfitsdata to pass and enable it.
Fixed SolverUtils and now memory issues no longer plague the testParallelSolver test, even with 10000 iterations!
The test was made more "stressful" by pre-loading all fits files, so it runs much quicker, and thus stresses the parallelism more. Updated golden values in other tests inside testfitsdata.cpp and made that an active stable test.