use ui buffering in changeset printer
delete old uibuffer class
delete old stringio class
move show to _show
add new show that uses ui.pushbuffer to buffer
add new flush that writes buffered data
add props arg to changeset_printer to match _templater
#!/bin/sh
mkdir t
cd t
hg init
echo "invalid" > .hg/hgrc
hg status 2>&1 |sed -e "s:/.*\(/t/.*\):...\1:"