[Cin] \LaTeX manual

[Andrea paz]

Add chapter 9.
There are several problems I bring back here and others I've put on
the \todo list:

1- I wrote a footnote to the "Native Video Effects" section. Since
this title also appears as a header of the right pages, the footnote
count goes up all the time.

2- I wrote the long list of FFmpeg plugins with a simple copy and
paste. Do you think it's okay?

3- I left the numbering of the subsections of the plugins titles. Do
you think it's better without numbering?