Typo in one of the shift_left_helper cases

I think the fourth case is when the first square is occupied but the second isn't.
Merge pull request #29 from curiousleo/patch-1

Typo in one of the shift_left_helper cases
Add instructions for cloning the repository (suggestion by @heidi-ann)
Say where to find the functions (suggestion by @heidi-ann)
Nest bullet points (suggested by @heidi-ann).
Link to instructions.
Add a test for the game over condition with completely empty boards.

Fixes #31.
Typo (thanks, @samoht).
Add BSD3 license and copyright notices.
Switch to BSD2.
Add appveyor file
Revert "Add appveyor file"

This reverts commit deb0a7e609953457fdc6d95a58ee224367dd58aa.
Functorize the solution code
Add local static tree for iocaml server
Add static files for iocamljs server
Clean canvas when starting the app (to have only one board)
Fix compilation of tests
Add 2048 notebook
Fix build
Improve the notebook