high memory persists in water calibrations (mostly d2h)

[rfiorella]

Memory still persists in d2h measurements used for calibrating water vapor data - effect on the standards is up to 10‰. Need to either perform better filtering, or implement a memory correction routine (c.f., van Geldern and Barth 2012).

Example: 1_monWStds_WREF - 2018 data.