chgserver: make S channel support pager request
This patch adds the "pager" support for the S channel. The pager API allows
running some subcommands, namely attachio, and waiting for the client to be
properly synchronized.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true