Add New Font (#72)

* Use upstream go-bdf library instead of our fork.

The zachomedia/go-bdf has our changes merged and it has fixes to the
bounds of the glyphs, which renders fonts much more nicely using pixlet.
For example, a colon now has the appropriate spacing.

* Added font embedding to the Makefile.

This commit adds the font embedding utility to the make file so that we
can embed new fonts on build.

* Added a font preview example.

This commit adds a preview to examples to preview new fonts in the repo.

* Added tom-thumb font.

This commit adds the Tom Thumb font found here: https://robey.lag.net/2010/01/23/tiny-monospace-font.html

This font is supy tiny and allows for packing some serious information
onto a display.

* Fixed false comment.

The all uppercase comment can be true, but we'd need to modify this
font. I honestly think we should add a tom-thumb-upper that has all
lowercase characters removed and the height set to 5.

Makefile

@@ -7,5 +7,8 @@ clean:
 bench:
 	go test -benchmem -benchtime=20s -bench BenchmarkRunAndRender tidbyt.dev/pixlet/encode
 
-build: clean
-	go build -o build/out/pixlet tidbyt.dev/pixlet
+build: clean embedfonts
+	go build -o build/out/pixlet tidbyt.dev/pixlet
+
+embedfonts:
+	go run render/gen/embedfonts.go

doc/fonts.md

@@ -97,3 +97,14 @@ including the runic code block. 4121 code points in total.
 - Ascent: 11
 - Descent: 2
 
+### tom-thumb
+By [Robey Pointer](https://robey.lag.net/2010/01/23/tiny-monospace-font.html)
+
+A very tiny, monospace, bitmap font. It's a 4x6 font (3x5 usable pixels) that's
+great for packing in information on your display.
+
+- Advance: 4
+- Height: 6
+- Cap height: 4
+- Ascent: 5
+- Descent: 1

examples/font-preview.star

@@ -0,0 +1,43 @@
+load("render.star", "render")
+
+def main(config):
+    font = config.get("font", "tb-8")
+    print("Using font: '{}'".format(font))
+    return render.Root(
+        child = render.Column(
+            children = [
+                render.Box(
+                    width = 64,
+                    height = 1,
+                    color = "#78DECC",
+                ),
+                render.Marquee(
+                    width = 64,
+                    child = render.Text("The quick brown fox jumps over the lazy dog", font = font),
+                ),
+                render.Box(
+                    width = 64,
+                    height = 1,
+                    color = "#78DECC",
+                ),
+                render.Marquee(
+                    width = 64,
+                    child = render.Text("THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG", font = font),
+                ),
+                render.Box(
+                    width = 64,
+                    height = 1,
+                    color = "#78DECC",
+                ),
+                render.Marquee(
+                    width = 64,
+                    child = render.Text("!@#$%^&*()_+:?><~`", font = font),
+                ),
+                render.Box(
+                    width = 64,
+                    height = 1,
+                    color = "#78DECC",
+                ),
+            ],
+        ),
+    )