Solution booklet

[VVitale]

This adds the solution booklet for examples 1-22 (15 excluded. It will be added shortly). The solutions to the remaining examples will be added ASAP.
The booklet style and layout mirror that of the tutorial.
In the doc directory there is a new folder, called solution_booklet, containing the .tex files and the figures, whereas the compiled pdf is in the compiled_doc folder.

DESCLAIMER: These are the solutions to the 22 examples for the v2.1 of Wannier90!
Also all the band-structures have been computed with ws_distance = .false., which was the default before #218.

[codecov]

Codecov Report

Merging #233 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #233   +/-   ##
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  Coverage    62.01%   62.01%           
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  Files           29       29           
  Lines        17161    17161           
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  Hits         10643    10643           
  Misses        6518     6518

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[giovannipizzi]

There are two leftover files starting with a dot (._...pdf) could you remove them?
Also, I'm wondering if it's worth adding the PDF to the git repository, making it much heavier, or we just keep the sources and put the PDF only on the website. Probably ok to keep it in for now, but we should make this decision also for tutorial and user_guide (I would vote for having these compiled by travis and then pushed automatically e.g. to the GitHub pages).

[VVitale]

Deleted the two extra .pdf files

[giovannipizzi]

Thanks!