XWIKI-10998: After a user deletes his avatar, "User Avatar" is not correctly displayed
- Added tests to preserve previous coverage.
XWIKI-11570: Add getCurrentWikiDescriptor() method to the wiki API to be consistent with the existing getCurrentWikiId() method
- Added missing test to ensure previous coverage.
XWIKI-11573: Make the automatically set Thread classloader dynamic
XWIKI-10708: Allow LESS syntax in SSX.

* Implemented a workaround because there is a bug in the LESS compiler with @import feature with the "reference" option.
* Delete all temp files properly.
XWIKI-11576: Create a CSS class to make a responsive table.
XWIKI-10735: Make History responsive.
XWIKI-11576: Create a CSS class to make a responsive table.

* Add @since comment.
XWIKI-11576: Create a CSS class to make a responsive table.

* Fix comment.
Merge branch 'master' into feature-less4j
XWIKI-10708: Allow LESS syntax in SSX.

* Revert the removing of included code because it prevents us to use .extend().
XWIKI-11034: Use LESS4J for the implementation of LESSCompiler.

* Remove unwanted dependency.