Refactor settings object, add connectTimeout setting.

Refactor settings object, add connectTimeout setting.

- include/util.js: Add type and desc field to conf_default routine.
  Make comment descriptions of settings into desc parameters that can
  be queried. Also, use set_FOO in conf_default to set or coerce the
  current setting so that we always have the right type for the value.

- include/rfb.js, include/default_config.js: add connectTimeout
  setting to address situations with slow connections that may need
  more than 2 seconds.