Metar Ice groups

[jimmyc42]

The METAR data has the 3 Ice groups ( I1XXX I3XXX I6XXX ) buried in the Remarks section. Ive taken a stab at trying to detect these instances of freezing rain accumulations, but my success rate is pretty low.
Honestly there are a few remarks worth extracting that would come in handy (e.g. PRESRR, PRESFR) so maybe a function for extracting a specified dict of remarks.
jimmyc

[sgdecker]

Issue #1727 includes some of this. I suppose the presence of things like PRESRR and PRESFR could be reported as booleans.