indent
Rework the way validation and param extraction works.

- Parameter validation is now done only when http_process_*()
  is called and upon http_argument_add().
- You MUST have defined your params in a param block or they will
  be filtered out.
- http_argument_lookup() is dead, welcome http_argument_get() and
  its brothers and sisters:
	http_argument_get_string()
	http_argument_get_uint16()
	http_argument_get_int16()
	http_argument_get_uint32()
	http_argument_get_int32()

  They will automatically do bounds checking on integers for you
  and return proper integers or a NUL-terminated string.

- The http_argument_get* functions no longer create an additional
  copy of the string which you need to free. Easier going.
- http_multiple_args() is dead, byebye
- Make some stuff we don't want to share with the modules static.