gitweb: Add new option -nohtml to quot_xxx subroutines

gitweb: Add new option -nohtml to quot_xxx subroutines

Add support for new option -nohtml to quot_cec and quot_upr
subroutines, to have output not wrapped in HTML tags.  This makes
those subroutines suitable to quoting attributes values, and for plain
text output quoting.  Currently this API is not used yet.

While at it fix whitespace, and use ';' as delimiter, not separator.

The option to not wrap quot_cec output in HTML tag were proposed
originally in patch:
  "Don't open a XML tag while another one is already open"
  Message-ID: <redacted>
by Robert Schiele.  Originally the parameter was named '-notag', was
also supportted by esc_html (but not esc_path) which passed it down to
quot_cec.  Mentioned patch was meant to fix the bug Martin Koegler
reported in his mail
  "Invalid html output repo.or.cz (alt-git.git)"
  Message-ID: <redacted>
which was fixed in different way (do not use esc_html to escape and
quote HTML attributes).

Signed-off-by: Robert Schiele <redacted>
Signed-off-by: Jakub Narebski <redacted>
Signed-off-by: Junio C Hamano <redacted>