bump version

Bump version, update CONTRIBUTORS, CHANGELOG

fix text selection hint

Changelog for v0.12.1

release: include resources PyInstaller doesn't record in spec files.

Bump version

Minor tweaks to release checlist and binary builds

always show error messages

Merge branch 'master' of ssh.github.com:mitmproxy/mitmproxy

Don't insist that the maintenance version of netlib match.