Don't use substripts in HTML if there is just a number in the
subscript: "R1", not "R<sub>1</sub>", except for characteristic
impedance. And of course still use "Z<sub>in</sub>", not "Zin".
This is also consistent with the images.
ix the problem with the original template-based implementation to limit
the amount of things that could be forgotten by new panel creators
(since we can't just have a static fail method warning about things
beinf forgotten).
This reverts commit a92516bcd2.
On wxWidgets 3.0, SetSizeHints must be called once the panel is fully populated.
On wxWidgets 3.1.5, SetSizeHints is not mandatory but can be called to ensure
right sizes once the panel is fully populated.