Added information on masked arrays to the Numpy page.

Added Euler Angle support (e.g. RPY) to the 3D rotations calculator.

New introduction to different map projections.

Added a new React page.

Updated the mv (move) page with information on using extended bash glob extensions to provide exclusion patterns.

$ mkdir new_sub_dir # Create a new sub-directory to move all files/directories in PWD into
$ mv !(new_sub_dir) new_sub_dir # Move all files/directories in PWD into new_sub_dir, excluding new_sub_dir itself (avoiding the obvious recursion problem)

The Introduction To Rotation Matrices page has been updated with tutorials/example on how to combine rotation matrices and how to calculate the rotation matrix to describe the rotation between two reference frames, as well as a section on how to convert RPY (roll-pitch-yaw, or Euler angles) to rotation matrices.

$$ \mathbf{R} = \begin{bmatrix} \hat{u_x} & \hat{v_x} & \hat{w_x} \\ \hat{u_y} & \hat{v_y} & \hat{w_y} \\ \hat{u_z} & \hat{v_z} & \hat{w_z} \end{bmatrix} $$

Added an interactive 3D rotation visualizer to the Quaternion page, which shows you how a right-hand coordinate system XYZ is rotated in 3D space by either a rotation matrix, quaternion, or angle-axis rotation. This tool is also very useful to convert between the three ways of describing a rotation (when you enter a rotation in one notation, the other two get updated automatically).

The du (disk usage) page now has information on the -x flag which is used count the space used on one filesystem only.

New Introduction To Asynchronous Programming In Python with information on asynchronous programming in Python, including the keywords async`/await`, event loops, futures, coroutines and more.

New tutorial on Standard Deviations.

Updated the Qt page with a section on how to allow file names with capital letters in Qt Creator.