Fixed assertion that were broken with recent delayed header response.
Changed semantic of put_header_lines and add_header_lines,
Now the arguments are iterable of string (i.e the header line)

The previous features were not used, and were not well named.
So we removed them, and reused the names for adpated implementation.
Fixed default status code for redirection response message object.
Added WSF_STARTS_WITH_AGENT_HANDLER
Extracted the WIDGET and FORM classes out of "cms" component
and build the wsf_html library which also include the previous css lib.
restored assertion removed by error
added wsf_html-safe.ecf to all-safe.ecf
removed obsolete call
use wsf_html lib in the demo
Added self doc to the wsf file system handler
Allow to hide the wsf file system handler from self documentation
Better description format handling for the self doc
Do not use socket_ok .. but readable  (as specified in precondition of read_stream_thread_aware
Added remove_header_named (a_name)
Moved more components from CMS to wsf_html.
This includes WSF_PAGER, and feature in WSF_THEME .. including WSF_API_OPTIONS
used to compute url and link.
allow to to set html attribute to the select widget
(useful to add code like  onchange="this.form.submit()")
fixed compilation