v0.4.0 - Arrays and matrices, optional \sqrt arguments, and more

New Features:

• Added support for some \begin/\end environments, including support for array, matrix, pmatrix, bmatrix, vmatrix, and Vmatrix
• Added support for optional \sqrt arguments, e.g. \sqrt[3]{x}
• Bower package is now available: run bower install katex to download the built files

Other changes:

• Add a display mode flag to the cli
• Expose an unstable __parse method for retrieving the parse tree
• Prevent elements from inheriting text-indent