NPM init
Add main.js and text parser module

The text parser generates an index of sentences categorized by the first
word which they start with.

I could have used 'split' to handle the initial seed text, but I prefer
to step through it one character at a time and parse it that way. This
is lighter on memory usage, and still performs in about linnear
complexity. It also gives some flexibility in parsing different types of
things - for example, I change newlines into spaces as I go. That
would be possible if using 'split', but it would work slightly
differently - it might take an extra step.
Clean up and test the text parser

Improvements:
 - trim whitespace from sentences
 - Skip underscores, dashes, and other spurious punctuation marks
 - Log a summary of the generated JSON in main.js
Mix up order of sentences when parsed
Add initial markov chain generator and fix bugs

This adds the initial version of the fiction generator, using a very
basic markov chain:
1. Find a sentence begining with your starter word. This is your 'found
sentence'.
2. Reset the 'starter word' to the word that began the sentence
following your 'found sentence'.
3. If at any point you run out of starter words or sentences that start
with those words, choose a random starter word from the possible starter
words.

To make this work, I lowercase all starter words when saving them with
the parser.

A test in main.js prints out a short piece of generated fiction.
Save generated fiction in markdown file

Details:
 - This is the second step of the 'generateFiction' method
 - It adds a header based on the title passed in the options
 - It titles the file based on the title of the chapter, but cleans the
   filename with a regex
Add parsed text JSON and generated test chapter