font issues on macOS

[jonorthwash]

DejaVu fonts are not on macOS by default, so the new controls look a little funny until they're installed. I guess it falls back to some other font, but I'm not sure which.

Three possible solutions:

1. Throw a warning on starting UltraTrace if the necessary fonts aren't detected. Ideally the warning should say how to get and install the fonts.
2. Have setup.py install the fonts.
3. Find a good fallback font for macOS—something that's standard on most installs.

I think all of these solutions can be implemented side-by-side.

[qiyoulu]

For 2: I made a PR with a new Python script that installs the fonts and made install.sh call it, instead of having setup.py install the fonts:
#189

[jonorthwash]

Could you do a mention of the issue in the PR or vice-versa, so that they're linked?

Also, this is only relevant for tkinter, and the plan is to move away from that, so this issue is pretty low priority.