Add a HandleReader Plugin

This adds a new `HandleReader` plugin, which displays data from a
Haskell `Handle`. This is really only useful if you are running xmobar
from within another Haskell program, but lets you avoid the mechanics of
creating a named pipe with the proper file permissions.

Instead, you can use `System.Process.createPipe` to make a pair of read
& write Handles. If you pass the read handle to HandleReader, you can
use hPutStr on the write Handle to send data to xmobar from your
application code.

1 files changed, 7 insertions, 0 deletions

diff --git a/changelog.md b/changelog.md
index a88e1ba..e147c22 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,10 @@
+## Version 0.34 (Unreleased)
+
+_New features_
+
+  - New plugin `HandleReader` for reading data from a Haskell `Handle`. This is
+    useful if you are running xmobar from within a Haskell program.
+
 ## Version 0.33 (February, 2020)
 
 _New features_