More coherent module names

The release of Eliom-2.2 contains the attempt of an easier and more coherent module hierarchy. This is achieved by the following principles:

• More intuitive module names (Eliom_content, Eliom_registration).
• Merge all functionality relating to (XML) content in Eliom_content.
• Module names are generally in lower-case form (except the first letter).
• Module names are generally given in singular.

A (partial) compatibility module is provided in Eliom_compatibility_2_1.

Migration alongside the CHANGELOG

• Dropped Eliom_pervasives, split into
  • Eliom_lib (extension of stdlib)
  • Eliom_content (content creation)

Solution: Add the following at the beginning of .eliom-files, or replace open Eliom_pervasives by:

open Eliom_content
open Eliom_lib

• Moved all HTML5,XHTML content function to Eliom_content.{Html5,Xhtml}
  • {HTML5,SVG,XHTML}.M → Eliom_content.{Html5,Svg,Xhtml}.F
  • {HTML5,SVG,XHTML}.DOM → Eliom_content.{Html5,Svg,Xhtml}.D
  • Eliom_output.{Html5,Xhtml}: form functions to Eliom_content.{Html5,Xhtml}
  • Eliom_client.Html5 → Eliom_content.Html5.To_dom
  • Eliom_dom → Eliom_content.Html5.Manip
  • HTML5.of_element → Eliom_content.Html5.Of_dom.of_element
• Rename Eliom_output to Eliom_registration
• Rename Eliom_registration.Eliom_appl to Eliom_registration.App

Solution: Renaming (carefully to decide between functions of former Eliom_output.XYZ which moved to Eliom_content.Xyz and those moved to Eliom_registration.Xyz.

• Removed default implementations in Eliom_content.{Html5,Svg,Xhtml} (was inclusion of DOM)

Solution: Make an explicit choice by opening/using either D or F.

• Conform naming conventions for modules (singular, lower-case)
  • XML → Xml
  • SVG → Svg
  • XML_types → Xml_types
  • XHTML_types → Xhtml_types
  • HTML5_types → Html5_types
  • Eliom_services → Eliom_service
  • Eliom_parameters → Eliom_parameter
  • Eliom_references → Eliom_reference
  • Eliom_extensions → Eliom_extension
  • Eliom_cookies → Eliom_cookie
  • Eliom_comet.Channels → Eliom_output.Channel

Solution: Simple renaming.