Adopt the New York Times style guide

Issue #246

I have added an Uncrustify configuration file to the project that should mostly match up with the New York Times Style Guide that we will now be following.

To use it, install BBUncrustifyPlugin. It will automatically detect the config file and allow quick cleanup of selected lines, the active file, or even a selection of files. If something seems inconsistent, install UncrustifyX, and use the Edit Uncrustify Configuration option to tweak the config. All of these options are in the XCode Edit menu.

I also updated the contributing guidelines to indicate use of the NYT style guide.