Feat/Data handler to save data #646

All 388 tests pass, 3 skipped in 23s

391 tests - 1 388 ✔️ ±0 23s ⏱️ -36s
    1 suites ±0     3 💤 ±0
    1 files ±0     0 ❌ - 1

Results for commit 7d620b4. ± Comparison against earlier commit 8d52ad9.