Dolfyn

- Bugfixes
- Fixed errors in docs and docstrings
- Skipped unknown TRDI Ocean Surveyor ID codes

- API/Useability
- Added CF convention metadata to variables

- Bugfixes
- Fixed errors in TRDI reader that caused ensembles to be skipped
- Variables found from NMEA data now all contain _gps tag
- Calculate VMDAS and WinRiver sampling frequency from diff of time coordinate
- Fixed bug that dropped shared but differing "lag" coordinate between auto-covariance
and cross-covariance functions
- Fix duty cycle attributes for some Nortek instruments
- Fix bug where 'accel' variable was rotated incorrectly in `correct_motion`
- Fix bug where ADV IMU variables could not be rotated to beam coordinates

- API/Useability
- Added the ability for the TRDI reader to search for the VMDAS navigation header
manually and determine which slot (nb vs bb) that VMDAS is saved in - Thank you jklymak!
- Clarified VMDAS navigation block variable names
- Added ability to read WinRiver2 NMEA data (GGA, VTG, HDT, DBT)
- Added ability to read TRDI 5th beam altimeter data
- Added ability to read RiverPro/StreamPro surface layer profile
- Updated TRDI attribute names
- Debugging readers now uses logging module
- Add 'fill_nan_ensemble_mean' function to ADV cleaning methods
- Spectra frequency coordinate name is set to 'freq', whether using radial (rad/s) or
classical (Hz) frequency units instead of 'omega' and 'f', respectively
- `correct_motion` is now capable of processing data from duty-cycled ADVs
- `CalcMotion` class is changed from private to public

- Bugfixes
- "calc_tke" function now errors if given multi-beam ADCP velocity vector
- Clean thresh function failed to remove spikes
- ADV despiking max gap input
- Fix input error to calc_L_int
- `dist_bt` and `prcnt_gd` variables should be in beam coordinates

- API/Useability
- Moved "calc_stress" and "calc_csd" functions to ADVBinner class
- Removed "do_tke" function
- Frequency units for calculating power spectral densities are consistently set to rad/s
- Made base PSD and CPSD functions public
- Renamed variable "stress" to "stress_vec" to stay consistent

- Bugfixes
- Detect missing timestamps in ADV binary files

- API/Useability
- Added classic Nortek instrument configuration details into dataset attributes

- Bugfixes:
- ADV and TRDI correlation and amplitude 'dir' dimension values
now remain in "beam" coordinates (96)
- Removed deployment height from surface interference cleaning
(`find_surface_from_P`) calculation
- Remove extra entry added to ADV time dimension when `read` is
given "nens" argument
- Auto-convert "maxgap" argument in ADCP "fillgaps_time" to numpy.timedelta64

- API/Useability
- Change functions in `TimeBinner` that use reshape (detrend,
demean, mean, var, std) from private to public

- Change the xarray dataset-accessor from `Veldata` to `velds`.
- Begin reimplementing DOLfYN API in the velocity.Velocity class (accessed via velds above)
- Switch from epoch time to datetime64 in datasets
- This also includes a bugfix where the epoch time was machine specific.
- No longer Python 2 compatible.
- Re-implement the 'inplace' argument for several API functions.

- Nortek Signature (.ad2cp):
- Fix some read issues
- Decoded binary 'status' variables
- Dropped 'temp_mag' (magnetometer temperature) - this thermistor isn't calibrated
- Added 'xmit_energy' (beam transmit energy in dB) into data variables