Pyjams

* Added `directory_from_gui`, `directories_from_gui`, `file_from_gui`, and
`files_from_gui`, GUI dialogs to choose directories and files using
Tkinter.
* Organize API reference documentation by categories.
* More consistent docstrings across routines.
* Bug in `alpha_equ_h2o` for scalar in/out.

* Added `fsread`, `fread`, and `sread`, reading numbers and strings from a
file into 2D float and string arrays.
* Changed order of color maps in printing and plotting.
* Edited docstrings of color module to follow closer numpydoc.

* Added `date2date`, which converts date representations between different
regional variants.
* Change documentation to Alabaster theme with custom CSS file.

* Use `text2plot` in `abc2plot` and `signature2plot`.
* Better handling of linebreaks in Matplotlib and LaTeX mode in `str2tex`.
* Added `text2plot`, adding text onto a plot.
* Added `int2roman` and `roman2int`, converting integer to and from
Roman literals.
* Combine `abc2plot` and `signature2plot` in one file `text2plot.py`.
* Added `abc2plot`, adding a, B, iii), etc. onto a plot.
* Added `signature2plot`, adding a copyright notice onto a plot.
* Added 'pyjams_color.pdf' as reference to available colormaps.

* Added tests for `color`.
* Added 'pragma: no cover' to plot and MPI sections of codes so that they
are not included in coverage report.
* Cleaned mcPlot docstrings.
* Cleaned formats in all docstrings.
* Added current colors of Paul Tol, i.e. sron color palettes.

* Add `position`, which positions arrays of subplots to be used with
Matplotlib's add_axes.