Add ansi theme to replace ansi-light and ansi-dark

This combines ansi-light and ansi-dark into a single theme that works
with both light and dark backgrounds. Instead of specifying white/black,
the ansi theme uses the terminal's default foreground/background color
by setting alpha=01, i.e. #00000001. This is in addition to the alpha=00
encoding where red contains an ANSI color palette number.

Now, `--theme ansi-light` and `--theme ansi-dark` will print a
deprecation notice and use ansi instead (unless the user has a custom
theme named ansi-light or ansi-dark, which would take precedence).

1 files changed, 3 insertions, 4 deletions

diff --git a/README.md b/README.md
index f84a2b5f..cbd83731 100644
--- a/README.md
+++ b/README.md
@@ -390,12 +390,11 @@ You can also use a custom theme by following the
 
 ### 8-bit themes
 
-`bat` has four themes that always use [8-bit colors](https://en.wikipedia.org/wiki/ANSI_escape_code#Colors),
+`bat` has three themes that always use [8-bit colors](https://en.wikipedia.org/wiki/ANSI_escape_code#Colors),
 even when truecolor support is available:
 
-- `ansi-dark` looks decent on any terminal with a dark background. It uses 3-bit colors: black, red,
-  green, yellow, blue, magenta, cyan, and white.
-- `ansi-light` is like `ansi-dark`, but for terminals with a light background.
+- `ansi` looks decent on any terminal. It uses 3-bit colors: black, red, green,
+  yellow, blue, magenta, cyan, and white.
 - `base16` is designed for [base16](https://github.com/chriskempson/base16) terminal themes. It uses
   4-bit colors (3-bit colors plus bright variants) in accordance with the
   [base16 styling guidelines](https://github.com/chriskempson/base16/blob/master/styling.md).