Various minor changes on merged versions.

1. Login with accounts9 feature is temporarily removed due to a missing
page accounts9_login.html.
2. Refined code formats and simplified a few statements.
3. Bug fix: ctrl+x hotkey for posting is removed due to the conflict
with default cut hotkey.
4. Bug fix: clicking on path terms will now correctly trigger the
loading icon.
REMARK: mail reading has been tested but all relevant UI design needs to
be optimized.