Add Seaglider data loading functions.

Add low level functions to load Seaglider from log and eng files:
  - `sglog2mat`: load data from a single log file.
  - `sgeng2mat`: load data from a single eng file.
  - `sglogcat`: cat data loaded from several log files.
  - `sgengcat`: cat data loaded from several eng files.
  - `sglogengmerge`: merge data loaded from several log and eng files.

Also provide a higher level function to load data
from all log and eng files in a directory.
  - `loadSeagliderData`
Honor data type in low level NetCDF functions.

`readNetCDFData` and `writeNetCDFData` now read and write
variables keeping their original data type if possible.
Otherwise they create ncdouble variable.
Rename low level NetCDF read and write functions.
Add C style string conversion function.

Function `strc.m` converts blank padded character arrays (Fortran
style) to null character terminated strings (C style).
Refactor NetCDF product generation.

Replace NetCDF product generation functions specific for each level
by a general function that updates deployment attribute values
and geospatial coverage attributes.

Add functions:
  - `generateOutputNetCDF`

Remove functions:
  - `generateOutputNetCDFL0`
  - `generateOutputNetCDFL1`
  - `generateOutputNetCDFL2`

Remove these functions
Adapt NetCDF product configuration functions to last changes.

Introduce separate configurations for level 0 Slocum and Seaglider
NetCDF data products.

Adapt other product configuration to new input format requirements
of modified NetCDF generation function.
Add new configuration functions for Seaglider data loading.

Seaglider data loading for real time and delayed time modes
is configured in new functions:
  - `configRTFileOptionsSeaglider`
  - `configDTFileOptionsSeaglider`

The name pattern of files to load is specified as a regular expression,
and parameters and data columns to load might be chosen.
The path to the files is configured in the same function for all kind of
gliders (`configRTPathsLocal` and `configDTPathsLocal`).
Adapt main glider processing scripts for initial support to Seaglider data.

Introduce modifications to handle both Slocum and Seaglider deployments.
For Seaglider, only data loading and raw product generation is performed
and only in delayed mode. Seglider data download and prepreprocessing
is still missing.
Refactor JSON support funtions.

Refactor JSON export function to escape characters when encoding a
string object and add a new function to import JSON data.
Move both functions to common tools directory.
Move lowlevel NetCDF functions to common tools.
Move figure export function to common tools directory.
Adapt main scripts and figure generation fucntion to last changes.
Add function to fill Seaglider missing GPS date stamps.
Change renaming for log parameters merged with eng columns.

Depth measurements in GC log lines are in meters,
while the ones in eng columns are in centimeters.
Hence they should not be merged.
Rename the depth from log lines to 'GC_depth' in merged output.
Add function to reverse Seaglider pressure-to-depth conversion.

Seaglider gliders do not report direct readings of pressure, but
approximate depth values computed using a constant conversion factor.
Function `sgdepth2pres` reverses that conversion.
Add function to calibrate CT sails mounted on Seaglider gliders.

Seaglider gliders report conductivity and temperature measurements
as frequency readings which should be converted to engineering units
using the equations and coefficients provided in Seabird calibration
sheets.

Function `calibrateSBECT` performs this conversion.
Add function to calibrate count data from WET Labs optic sensors.

Data from the optic sensors by WET Labs like the ECO Triplet Puck
mounted on Seaglider gliders are reported in counts.
They may be converted to engineering units by applying linear equations
with the coefficients provided in the calibration data sheets.

Function `calibrateWLECOBBFl2` performs this conversion.
Add pressure conversion function.

Pressure is used in decibars but some sensors repors it in bars.
Even though the conversion is simply a factor of 10,
it is convenient to provide a named function `bar2dbar`
to perform it when needed.
Extend nmea conversion function to support pairs of arguments.
Switch arguments of Seaglider GPS timestamp filling function.