concat: Allowed to pickle the results instead of writing csvs
Added a requirement spec with working versions of the dependencies.

There seems to be a bug with newer versions of numpy that needs to be
evaluated sometime
delta: Tokenizing does no longer use numbers
concat-deltas: Allow short filename format
evaluate: Allow to run on frequency table instead of corpus
Added an option to corpus to get the word counts instead of frequencies
Use absolute word count to sort the word list.

This involves a change in processing: Corpus(subdir) will now be a table
of word counts, but it will already be sorted. Corpus.get_mfw_table(n)
will then calculate the frequencies and slice the upper n words.
Made the plot points a little smaller