Add support for vertical mod

[otzi5300]

Closes #596

Step 2 of 4 in implementation of vertical skills

General idea of vertical skill is to store data for model and obs in 1d (see below). Depth information is stored in auxilary coordinate z. Befinit of this compared to storing in 2d:

• Similar to current data structures and current matching workflow can be used
• Allowing varying z coordinates for obs and sigma layered models

Steps:

1. BRANCHED FROM Support vertical obs
2. Support vertical model items
3. Matching to get comparer
4. plotting/skill etc on vertical

Features added in this PR

Support vertical obs per commit

(see vertical skill notebook for more info)
VerticalObservation class
Stores timeseries data for vertical profiles.

Validate timeseries with geomtype=vertical.

• Adds vertical geometry type
• Adds additional check for zcoord if gtype is vertical

parse input for timeseries with vertical coordinate.
Very similar to parsing of tracks (_track.py) but z-coordinate is now needed.

• remove duplicated (time,z) pairs. Note, duplicated time allowed ( obs with same time on multiple depth)

data structure:
time(time) = [t1, t1, t1, t2, t2, t2, t3 ...]
z(time) = [z1. z2, z3, z4, z5, z6, z7 ...]
data(time) = [d1, d2, d3, d4,d5,d6,d7....]

Testdata

• 3d sigma model (cut to very small domain)
• observations (2 locations) stored as dfs0 and csv

Tests of new features