use improved timedelta formater in havengetallen plotting functions

[veenstrajelmer]

Todo:

• [x] also use kw.utils.TimeSeries_TimedeltaFormatter_improved to tick timedelta on xaxis in kw.plot_aardappelgrafiek()
• [x] prevent manual ticks just like other timedelta figure

Code to reproduce:

import hatyan
hatyan.close("all")
import kenmerkendewaarden as kw
# import logging
# logging.basicConfig(format='%(message)s') # for some reason calling basicConfig is required for hatyan, not for kenmerkendewaarden
# logging.getLogger("hatyan").setLevel(level="INFO")

print("reading datafiles")
file_dia_ext = r"c:\DATA\kenmerkendewaarden\tests\testdata\HOEKVHLD_ext.dia"
df_ext = hatyan.read_dia(file_dia_ext, station="HOEKVHLD", block_ids="allstation")#, block_ids=[5,6,7,10])
df_ext = df_ext.loc["2018":"2019"]
df_ext = hatyan.calc_HWLW12345to12(df_ext)

print("computing indicators")
df_havengetallen = kw.calc_havengetallen(df_ext, min_coverage=None)
kw.plot_aardappelgrafiek(df_havengetallen)