[REF][MOV] documentation apocalypse

Prior to this commit, the Odoo documentation was mainly split between
two repositories: odoo/odoo/doc and odoo/documentation-user. Some bits
of documentation were also hosted elsewhere (e.g., wiki, upgrade, ...).
This was causing several problems among which:
  - The theme, config, Makefile, and similar technical resources had to
    be duplicated. This resulted in inconsistent layout, features, and
    build environments from one documentation to another.
  - Some pages did not fit either documentation as they were relevant
    for both users and developers. Some were relevant to neither of the
    two (e.g., DB management).
  - Cross-doc references had to be absolute links and they broke often.
  - Merging large image files in the developer documentation would bloat
    the odoo/odoo repository. Some contributions had to be lightened to
    avoid merging too many images (e.g., Odoo development tutorials).
  - Long-time contributors to the user documentation were chilly about
    going through the merging process of the developer documentation
    because of the runbot, mergebot, `odoo-dev` repository, etc.
  - Some contributors would look for the developer documentation in the
    `odoo/documentation-user` repository.
  - Community issues about the user documentation were submitted on the
    `odoo/odoo` repository and vice-versa.

Merging all documentations in one repository will allow us to have one
place, one theme, one work process, and one set of tools (build
environment, ...) for all of the Odoo docs.

As this is a good opportunity to revamp the layout of the documentation,
a brand new theme replaces the old one. It features a new way to
navigate the documentation, centered on the idea of always letting the
reader know what is the context (enclosing section, child pages, page
structure ...) of the page they are reading. The previous theme would
quickly confuse readers as they navigated the documentation and followed
cross-application links.

The chance is also taken to get rid of all the technical dangling parts,
performance issues, and left-overs. Except for some page-specific JS
scripts, the Odoo theme Sphinx extension is re-written from scratch
based on the latest Sphinx release to benefit from the improvements and
ease future contributions.

task-2351938
task-2352371
task-2205684
task-2352544

Closes #945

content/legal/licenses/licenses.rst

@@ -0,0 +1,120 @@
+
+.. _licenses:
+
+========
+Licenses
+========
+
+.. _odoo_community_license:
+
+Odoo 12 Community Edition
+=========================
+
+Odoo 12 Community Edition is licensed under
+`LGPL version 3 <http://www.gnu.org/licenses/lgpl-3.0.en.html>`_  (also known as LGPLv3).
+See also the `GPL FAQ <http://www.gnu.org/licenses/gpl-faq.en.html>`_ and the
+`compatibility matrix <http://www.gnu.org/licenses/gpl-faq.en.html#AllCompatibility>`_.
+
+
+.. _odoo_enterprise_license:
+
+Odoo 12 Enterprise Edition
+==========================
+
+Odoo 12 Enterprise Edition is licensed under the Odoo Enterprise Edition License v1.0,
+defined as follows:
+
+.. use <tt> to avoid default <pre> styling
+
+.. raw:: html
+
+    <tt>
+
+.. include:: enterprise_license.txt
+
+.. raw:: html
+
+    </tt>
+
+
+.. _odoo_apps_license:
+
+Odoo Apps
+=========
+
+Unless otherwise stated, Odoo Apps by Odoo SA (including the website themes) are published under
+the Odoo Proprietary License v1.0, defined as follows
+
+.. use <tt> to avoid default <pre> styling
+
+.. raw:: html
+
+    <tt>
+
+Odoo Proprietary License v1.0
+
+This software and associated files (the "Software") may only be used
+(executed, modified, executed after modifications) if you have purchased a
+valid license from the authors, typically via Odoo Apps, or if you have
+received a written agreement from the authors of the Software (see the
+COPYRIGHT file).
+
+You may develop Odoo modules that use the Software as a library (typically
+by depending on it, importing it and using its resources), but without
+copying any source code or material from the Software. You may distribute
+those modules under the license of your choice, provided that this license
+is compatible with the terms of the Odoo Proprietary License (For example:
+LGPL, MIT, or proprietary licenses similar to this one).
+
+It is forbidden to publish, distribute, sublicense, or sell copies of the
+Software or modified copies of the Software.
+
+The above copyright notice and this permission notice must be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+
+.. raw:: html
+
+    </tt>
+
+.. _odoo_11_license:
+
+Odoo 11
+=======
+
+The licenses for both editions of Odoo 11 were respectively the same as for
+:ref:`odoo_community_license` and :ref:`odoo_enterprise_license`.
+
+.. _odoo_10_license:
+
+Odoo 10
+=======
+
+The licenses for both editions of Odoo 10 were respectively the same as for
+:ref:`odoo_community_license` and :ref:`odoo_enterprise_license`.
+
+.. _odoo_9_license:
+
+Odoo 9
+======
+
+The licenses for both editions of Odoo 9 were respectively the same as for
+:ref:`odoo_community_license` and :ref:`odoo_enterprise_license`.
+
+.. _odoo_8_license:
+
+
+Odoo 8
+======
+
+Odoo 8 is licensed under
+`AGPL version 3 <http://www.gnu.org/licenses/agpl-3.0.en.html>`_  (also known as AGPLv3).
+See also the `GPL FAQ <http://www.gnu.org/licenses/gpl-faq.en.html>`_ and the
+`compatibility matrix <http://www.gnu.org/licenses/gpl-faq.en.html#AllCompatibility>`_.