Improve havengetallen

[veenstrajelmer]

Todo 2024:

• Align havengetallen and tidalindicators #79
• Investigate removing hard-coded moonculmination/extreme offset #103
• neater timezone handling and time corrections in calc_havengetallen #162
• reconsider 20 minute correction in culm_addtime for calc_havengetallen #164
• pass complete measurement series throughout code #166
• align code with min_coverage and modular newyear clipping #167
• apply slotgemiddelden to havengetallen and gemiddeldgetij #171

Todo 2025:

• Optional data corrections #29
• Consider using moon phases instead of moon culminations to compute havengetallen #174
• blocker for some stations: Fix numbering of extremes for havengetallen #101
• calc_havengetallen uses median, but calc_HWLW_springneap uses mean (just like calc_HWLWtidalindicators), fix this discrepancy. Since we do not scale timing of gemiddeldgetij anymore, a mean might not be so bad anymore.
• aardappelgrafiek is very messy for HOEKVHLD and other stations with aggers, is this solveable?