--> option `--cbar-fontsize`

In addition, gridlines fix for non-PlateCarree projections.

+ bugfix backslashes in title (e.g. necessary for '\n')

* Renamed options:
  * `markers` --> `show-mk`
  * `marker-size` --> `mk-size`

* New options:
  * `legend-mk-scale`
  * `mk-beg-lsty`
  * `mk-end-lsty`

--> See `--help` for details.

In short, the most important new feature is:
allow to define a different line style for
the markers at the beginning and end of storm track, in order to easily
know the direction of the storm along its trajectory.

Both methods (by name only or by label "name YYYY") are accepted by the
option `--sel-storms` and may be mixed in one single command, e.g.:
--sel-storms="wilma 2005,andrew"

In addition, there's a new option for selecting the projection, see `--proj` and `--proj-arg`.

This is pure cosmetics.

Replaces `--foo FOO` by `--foo=FOO` in the argparse helper.
Although there is always the possibility to use either `--foo FOO`
or `--foo=FOO`, it is sometimes better to document the '=' way
rather than the normal ' ' way.
For example, when the option argument contains special
characters like ',' it must be expressed with '=' in order to
not confuse the shell that executes the command line.

`--sel-storms`. See `--help` for details.

`--title` and `--title-fontsize`

See `--help` for details.

New options: `--marker-size` and `--legend-loc`.
See `--help` for details.

Minor refactoring to prepare for defaults dump in config file.

`--colormap`

To install:

pip install [URL of package -so far unset-]

`--no-markers` allows to avoid to show the markers (useful when many
tropical cyclones are plotted, because markers are slow to plot and will
clutter the whole figure).

Legend and symbols improvements + new option `--legend-ncol` to be able
to specify the number of columns to be displayed in legend.

New options are `--inc-lon` and `--inc-lat` to control to gridline
increments.

Options to limit the plotted area.
Same syntax as for other range options.

Still a few cosmetics ToDos w.r.t this feature.

[WIP] to fine-tune...

These 2 options allow to select storms based on resp. year range and
maximum category reached.

See --help for details.

This is WIP! The script is not fully functional yet.