Versions 0.3-0.7 Release Notes

[ChatGPT summary] Between versions 0.3d and 0.7.0, the python-control package underwent significant enhancements and refinements. Key additions included support for discrete-time systems with a timebase variable and the introduction of the c2d function for MIMO state-space systems. New functionality such as rlocus, pade, and nichols was added, along with minimal realization tools and model reduction methods like hsvd, modred, and balred. Plotting capabilities were expanded with more flexible Bode and Nyquist plots, frequency labeling, and a phase_plot command for 2D nonlinear systems. Performance improvements included faster versions of freqresp and forced_response, bug fixes in tools like dare and tf2ss, and enhanced stability margin and root-locus calculations. Installation became easier via pip and conda, Python 3 compatibility improved, and extensive documentation updates ensured a smoother user experience.