[gaia] RESTART MODE for GAIA like in TELEMAC-2D and TELEMAC-3D

Partially closes #756 and #899.

See merge request !121

First part.
Partially closes #756 and #899.

Major improvements:
- automatic saving of variables in the RESTART FILE necessary to continue a
GAIA computation at the wished records and not every graphic printout,
- as necessary variables are not saved in the RESULT FILE anymore
(in particular at every graphic printout), this last file is smaller in size
(e.g. with CO sediments),
- no loss of accuracy when continuing a computation.

New keywords:
- RECORD NUMBER FOR RESTART,
- RESTART MODE,
- RESTART FILE,
- RESTART FILE FORMAT,
- RESTART FILE PRINTOUT PERIOD,
- RECORD NUMBER IN RESTART FILE.

Examples in:
- mud_conservation-t2d,
- yen-t2d (multi 1),
- littoral-t2d-tom (triple coupling).

Updated GAIA reference files due to less stored variables (CO type sediments).

NB: some continuations of computation are not currently perfect (loss of
accuracy) and need to be investigated (coupling with TELEMAC-3D, CVSM...).

after SHA 6a5eaa96
(bump-t2d, canalalgae + riv_art)

3D windtel2tom, a test case has been added to test tel2tom in 3D with wind

See merge request !117

adding spin up functionality for bedload, suspended sediment transport, consolidation and sediment slide.

See merge request !105

- bed updates can be skipped in a first period of the simulation,
defined by users
- new keyword: SPINUP TIME FOR BED UPDATAING
- the yen test case is used to test this feature
- update user doc

Required in particuler in GAIA user documentation.

[scripts] Fix of URL of Corine Land Cover database and add of year 2018 data

See merge request !118

Remove SISYPHE from the whole system

See merge request !107

Reorganization of chapter 2 (no more distinction between NCO and CO
sediments since no necessary for advection-diffusion equation).
Several updates, suppression of obsolete/non existing functions.
Description of some missing keywords.
Suppression of useless keywords in dico: NUMBER OF SUB-ITERATIONS,
THETA IMPLICITATIONS FOR SUSPENSION.

as useless ("VERTICAL DIFFUSION ONLY")

as the keyword OPTION FOR THE DIFFUSION was removed in v7p3 + typo in French
help, thanks to Sara

The header does not fit check_code.sh script rules:
even number of columns is expected before starting to write

Useless since release v6p0!
It was used when calling PROPAG by TELEMAC3D subroutine.
Thanks to Sara's remark

MAXIMUM NUMBER OF FRICTION DOMAINS not MAXIMiM NUMBER OF FRICTION DOMAINS

CONTINUITY CORRECTION ON OPEN BOUNDARIES

[tomawac] Next computation with a wind, water depth or current given by a file

See merge request !113

Take into account the snow rate if given in the meteo file in KHIONE

See merge request !112

[scripts] Add features to MascaretGeoFile and Section (1D) classes + code-style correction & docstring

See merge request !115

Corrections in the vnv notebook example to the new name of some function
of Section class and one fix to detect the right geometric format for
MascaretGeoFile class

+ upate of NEWS.txt for modifications of Mascaret file Python Classes

Add a method to MascaretGeoFile class to generate a GIS file with the
format of PreCourlis (specific attributes to describe geometry and
other Mascaret-Courlis informations)

Adaptations to the new name for the definition of sediment layers in
Section class

Change the name of the original function for adding sediment layer to a
MascaretFile

Add an attribute to the class (topo-bath) to Section class to store
minor/major bed limit in profiles

Some corrections of syntax and add docstring

Add reading of topo-bath information which is given by a string in the
geometry file for each points of each profile ("B" stand for bathymetry
and "T" for topography). This information is used to mark the limits
between minor and major bed.

Add reading Courlis geometry files (geoC and georefC)

Add an option to the class to activate or desactivate loading of the
file

+ some syntax corrections