Simplify copyright

Fix CDF of F distribution

The CDF formula of the F distribution contained a typo where d_1 got
repeated twice instead of being once d_1 and once d_2.

Reported by Catherine Tousey.

Fix typo in expectation relationship

Resolves mavam#19

Bump version to 0.2.3

Bump version to 0.2.2

Fix variance of Pareto distribution

Spotted by Carlo Cavalieri.

Embed version in LaTeX source

This avoids bug with some LaTeX compilers which have trouble using
\input for files without extension.

Resolves mavam#15.

Consistently use Gamma & Exponential distribution

Textbooks use the beta parameter with different semantics. Some use it
as rate parameter and some as inverse scale. This commit switches
Gamma and Expoential distribution over to the rate parameterization, and
adds a footnote to clarify this notational inconsistency.

Closes mavam#13.

Fix plots of exponential and gamma

Reported by Farid Cheraghi.

Fix typo in index of summation

Reported by Carsten Oppitz.