This is recommended for macOS Tahoe and all standard menu items now have
associated images. This makes our app look more polished and native for
macOS Tahoe.
For icon choice, I tried to copy other native macOS apps as much as
possible, mostly from Xcode. It looks like a lot of apps aren't updated
yet. I'm absolutely open to suggestions for better icons but I think
these are a good starting point.
One menu change is I moved "reset font size" above "increase font size"
which better matches other apps (e.g. Terminal.app).
