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.
Cleaned mail viewing scripts

1. fix api calling. 2. move mail viewing functions to bbs_mail.js 3.
wrapping ansi2html function. 4. adding corresponding constants to
config.js 5. removing duplicate bbs_post_info declaration.
Cleaned mail ui codes

1. re-fixing path term bug on no responding. 2. removed or commented all
functions on writing mails. 3. consistent ui for mail content viewing
and post content viewing. 4. adding comments.
structuring const strings, settings into json
Refining mail viewing UI, bug fix, minor reorg.

1. adding navigation bars on mail listing.
2. adding paging on mail listing
3. bug fix: reach first page notification might not trigger
4. bug fix: bottom jump-to bar may not work correctly.
5. various other minor changes.
Adding mail view navigations

binding hotkeys to mail viewing and listing.
Add second redirection to solve security problem
All format cleaning

CRLF->LF, tab->4 spaces
saved in UTF-8 without BOM
...
Various changes tested.

1. auto scaling for HD screens.
2. fixed a bug on bottom "more options".
3. jump to top on hotkeys, clicks on entries and buttons.
4. compact footer.
5. uncommented file upload UI's for futher dev.
6. fixed a bug on location.origin unavailable on firefox.