Separated bibliography into sites and references

websites.bib contains sites that I used for my dissertation, but which
should probably be inserted as footnotes in the text.

mendeley.bib is (semi-)automatically generated by Mendeley's export
function. There are some minor mishaps that should be abstracted into
the Makefile.
Updated introduction.tex

Minor changes overall. There should be some changes to the "document
structure" part of it, regarding what has changed between the last and
the current report.
Initial chapter on probabilistic models

There's a brief explanation of what is a model, specifically a
probabilistic one.

The part on the Markov property could receive a bit of love--it's not
very well-explained, as there could be some example shown, using the
Markov Chain. One good example is the "weather model" from Rabiner's
tutorial (and Wikipedia).

The part on HMMs is definitely poor. Even if the three problems were
described correctly, their solutions are important also.

Another thing that I've missed is a diagram showing how a HMM works,
similar to the Markov Chain example. Again, the weather example from
Wikipedia seems like a good one here. The "ball and urn" problem from
Rabiner's tutorial is also interesting.
Added lots of information regarding NLP

Discussions and definitions regarding trigram language models and POS
tagging were added by Peter. Lots of extra discussions as well.

There's only one problem: it could use much of the probabilistic
framework exposed in the prob-models.tex chapter, simplifying the
explanations. However, this should be done now, with a good "initial
value".
Minor changes to lots of files

This commit is a set of very simple changes overall, but most of them
are important nonetheless. The most insignificant one is in
`appendices.tex`, which is to remember me to write about how to
reproduce experiments from my dissertation.

`schedule.tex` and `conclusion.tex` both resulted from other (major)
changes to the dissertation, i.e. they reflect actual content changes.

I added new packages to `tcc.tex`: `url` is used to improve the
bibliography and `tikz` is used to draw diagrams for markov chains. In
the future, I'll add hidden markov chains as well.

As for the bibliography, I added a new paper to `mendeley.bib`.

That is all.
Create figures from Makefile

I added a new rule to Makefile that uses LaTeX and Imagemagick's command
line interface to create a Markov chain figure.