Get the PDF build working

[moorepants]

It would be nice to have a PDF version of the text. There are several things to consider:

• [x] SVG's won't show up in the PDF build (maybe convert to PDF on the fly).
• [x] Build PDF without errors.
• [x] Build PDF in CI and make available for download.
• [ ] Animations will not display, how to handle them.
• [x] The bolded unit vectors look bad, make new printer to use the correct notation.
• [ ] It is difficult to tell the difference in the input code cell and the output code cell. (see https://github.com/jupyter/jupyter-sphinx/issues/208)
• [x] Each rst file should display as a chapter.
• [ ] SymPy math output that is long does not wrap.
• [x] The external figures from wikipedia are not included.
• [ ] The download links for the .py and .ipynb are not hyperlinks. (maybe don't show in latex version)
• [ ] TODO's show up in the latex output.
• [ ] Figure out how to hide some of the code (dropdowns and display:none) in latex.
• [ ] Display static thumbnails of youtube videos (or not)
• [ ] The jupyter-execute hidden cells are shown in the PDF

[moorepants]

Some errors:

! You can't use `\spacefactor' in math mode.
\@->\spacefactor 
                 \@m {}
l.2867 \(\LaTeX
               \) code. The double backslashes are present because double
? 
Missing character: There is no è ("E8) in font cmex10!
[29] [30]
Overfull \hbox (1033.02734pt too wide) detected at line 3221
[]
[31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45]
[46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56]
! Missing { inserted.
<to be read again> 
                   \gdef 
l.5585 \(\mbox{proj}_\hat{u}
                             \bar{v} = \bar{v} \cdot \hat{u}\)
? 
! Missing { inserted.
<to be read again> 
                   \gdef 
l.5585 \(\mbox{proj}_\hat{u}
                             \bar{v} = \bar{v} \cdot \hat{u}\)
? 
! Missing } inserted.
<inserted text> 
                }
l.5585 ...hat{u} \bar{v} = \bar{v} \cdot \hat{u}\)
                                                  
? 
! Extra alignment tab has been changed to \cr.
<template> }$\hfill \endtemplate 
                                 
l.13997 ...r{F}(\bar{u}, \bar{q}, t) \\\end{split}
! Extra alignment tab has been changed to \cr.
<template> }$\hfill \endtemplate 
                                 
l.13997 ...r{F}(\bar{u}, \bar{q}, t) \\\end{split}

[moorepants]

\mbox{proj}_\hat{u} should be \mbox{proj}_{\hat{u}}, see https://tex.stackexchange.com/questions/200561/how-to-resolve-the-error-missing-inserted-inside-an-algorithm2e

[moorepants]

:math:\LaTeX`` is incorrect, as it isn't a Math command in latex.

[moorepants]

PDF now builds without errors in 4db316b83c10a9e22418908c77a98aa1d7e41081

[moorepants]

Youtube embed does not show up:

[moorepants]

Youtube could be fixed by #86