New, more consistent terminal font

[jamwaffles]

Hi! Thank you for helping out with SSD1306 development! Please:

• Check that you've added documentation to any new methods
• Rebase from master if you're not already up to date
• Add or modify an example if there are changes to the public API
• Add a CHANGELOG.md entry in the Unreleased section under the appropriate heading (Added, Fixed, Changed, etc)
• Run rustfmt on the project with cargo fmt --all - CI will not pass without this step
• Check that your branch is up to date with master and that CI is passing once the PR is opened

PR description

This font is taken from the ATIx_550_8x8.png font image from the
romfonts repo. I picked it because it looks nice, but that's subjective. It looks like this:

I don't have hardware to test with tat the moment so I might have messed
up the character mappings. I'd appreciate if someone could test on a
physical display and see how this looks.

I'm not including any of the special characters defined in that font. If
we want to add them, I'd suggest we do that in a future PR.

Closes #135

[therealprof]

This font is taken from the ATIx_550_8x8.png font image from the
romfonts repo.

Could there be a copyright issue?

It's certainly very retro. ;)

[jamwaffles]

Yeah, I did think about copyright but decided to use it anyway 😬.
Should we continue with the current choice anyway?

The Uzebox wiki has some alternative 8x8 fonts but a) "Some may still be under copyright" and b) I can't be bothered to turn the bitmaps into hex :(

[therealprof]

Have you checked out sites like: https://jared.geek.nz/2014/jan/custom-fonts-for-microcontrollers ?

[jamwaffles]

I haven't, thanks for the link! Any idea what the copyright is like? I'll have a look through those fonts and find something suitable.

[jamwaffles]

Honestly, none of them look that good. I'm ok going with the original font for now.

[jamwaffles]

I took some time to switch to zxpix from https://jared.geek.nz/2014/jan/custom-fonts-for-microcontrollers. It's converted from TTF to bitmap, so there were some artifacts in a few of the characters, mostly the lowercase ones. I've fixed those manually. Licensing shouldn't be an issue now.

[jamwaffles]

Looks like this now.

[therealprof]

Nice! 👍