As I planned, version 2.4.1 introduces unit tests to the project. They can be run from the page UnitTests.html. The unit tests did help me ferret out a few bugs and help me verify that exponentiation of complex numbers was being done correctly.
The major new feature of this version is that you can now raise a complex number to a complex argument, expanding the number of fractals you can draw!
Version 2.4.0 fixed a bug where images were being drawn upside down. This was a big deal because some fractals, such as the "Burning Ships", are almost always presented upside down, so it took quite a bit of work before I realized what was going on. I fixed this bug in the process of fixing the bug where wrong numbers were being displayed for the imaginary coordinates in the complex plane.