r6998: - added support for application[] data, which is global to all clients using...

r6998: - added support for application[] data, which is global to all clients using the web server.
  This allows for things like
     application['state'] = "shuttting down"
  and then every web client can see that the server is going down

- added support for session[] data. This allows web pages to store
  long term data specific to this client. It relies on
  cookies. Sessions auto timeout (default timeout 5 minutes). The
  timeout can be set in the scripts.

- changed from processing all .html files as esp, to only processing
  .esp files as esp. This makes it easier to compare the samba web
  server to appWeb as a reference implementation.

- expanded the number of standard variables setup by esp. See the
  showvars.esp example page for all variables.
(This used to be commit c418b23c2ea383da8fad21b62213ec01fd135ebb)