* Remove the LESS configuration property which is eventually not used.

XWIKI-11394: Being able to overwrite a LESS file within a skin object.

* Fix.

XWIKI-11394: Being able to overwrite a LESS file within a skin object.

* Velocity should be only executed on the main skin file, not on any file with the ".less.vm" extension.

* Moved no longer used keys to the deprecation section

[Misc] Better error reporting (I did this initially in the context of trying to fix a flickering MailTest test but in the end I think it's flickering for a different reason). Still committing since it looks better than what we had before ;)

XWIKI-11394: Being able to overwrite a LESS file within a skin object.

[misc] Try to determine why the extension tests fail randomly with "We couldn't find any extension with id ...".

* fix test

* The extension plan display is not consistent with the dependencies display
* Update the test page objects.

XWIKI-11793: "Current wiki" wiki macros not available in the macros list in Dashboard in path based multiwiki

- Added missing "this." qualifier that was causing the add gadget button to not work. Thanks to @lavadiablo for pointing it out.

* Upgrade to less4j 1.9.0

Conflicts:
	xwiki-platform-core/xwiki-platform-lesscss/xwiki-platform-lesscss-default/src/main/java/org/xwiki/lesscss/internal/compiler/CachedIntegratedLESSCompiler.java
	xwiki-platform-tools/xwiki-platform-tool-configuration-resources/src/main/resources/xwiki.properties.vm

* Upgrade to less4j 1.8.5

* moved xalan management to commons since it's a dependency of jdom

* bulletproofing

* fix custom extensions.xwiki.org code included by mistake

* Fix FLAVOR-12 and FLAVOR-13 that also concern xwiki-platform (no issue for that since XWiki 7.0M2 is not released yet).

* add a few more categories
* display and edit category in the extension