thread: drop the use of urwidtrees

Their API is misdesigned - forces the use of trees for nontree objects
and mixes data relationships with display properties. The result is a
mess that is hard to understand/maintain/extend.

Replace the use of urwidtrees with urwid Pile and ListBox. This
temporarily removes tree-style indentation and decorations for thread
buffers. That will be reimplemented in following commits.

1 files changed, 0 insertions, 1 deletions

diff --git a/setup.py b/setup.py
index 5e95cd3e..67628890 100755
--- a/setup.py
+++ b/setup.py
@@ -46,7 +46,6 @@ setup(
     install_requires=[
         'notmuch>=0.27',
         'urwid>=1.3.0',
-        'urwidtrees>=1.0',
         'twisted>=18.4.0',
         'python-magic',
         'configobj>=4.7.0',