Fix lint errors and warnings.

arithmetic_integers: remove >100 char line.
hailstone: remove >100 char line and minor nits.
lzw: Remove ~str, remove >100 char line and fixed spacing.
parallel_calculations: remove trailing spaces, minor simplifications.
markov_algorithm: remove >100 char line, remove ~str.
Additional cleanup and ~str removal.

a+b: Simplify.
ackermann_function: remove to_str().
fasta: remove ~str.
integer_sequence: remove to_str().
rot13: remove ~str.
Merge pull request #105 from Ryman/lint_fixes

Fix lint errors and warnings.
Update README.md

Needed some cleaning and additional info. I'd like to get a better description of the test flags. @jschaf might know something about it.
use a table to display links
Merge pull request #106 from jschaf/readme-table

use a table to display links
add more explanation about testing
Merge pull request #107 from jschaf/readme-tests

add more explanation about testing
Fix build
Fix build
No need to modify accumulator in `fold` iterator.
Merge pull request #108 from utkarshkukreti/fix-fold

No need to modify accumulator in `fold` iterator.
Implement 100 doors unoptimized version
Merge pull request #109 from pfalabella/100doors-unopt-impl

Implement 100 doors unoptimized version
Fix build
fix 100doors_unoptimized trailing whitespace and clean code
Merge pull request #111 from pfalabella/100doors_unopt_fix1

fix 100doors_unoptimized trailing whitespace and clean code
 Created 9 billion names of God the integer
Fixes and another test
added implementation of Hamming numbers (ported from scala)