Add limited support for named colors

Resolves #41

tests/color_test.py

@@ -0,0 +1,15 @@
+import pytest
+
+from babi.color import Color
+
+
+@pytest.mark.parametrize(
+    ('s', 'expected'),
+    (
+        ('#1e77d3', Color(0x1e, 0x77, 0xd3)),
+        ('white', Color(0xff, 0xff, 0xff)),
+        ('black', Color(0x00, 0x00, 0x00)),
+    ),
+)
+def test_color_parse(s, expected):
+    assert Color.parse(s) == expected