XWIKI-10212: Implement a (Color) Theme Application for Flamingo.
XWIKI-10707: Provide a ColorTheme designed for Flamingo Skin.
XWIKI-10212: Implement a (Color) Theme Application for Flamingo.

* Add a translation key
XWIKI-10212: Implement a (Color) Theme Application for Flamingo.

* LESS cache is cleared if a flamingo theme is updated
XWIKI-10212: Implement a (Color) Theme Application for Flamingo.
XWIKI-10770: Make a clear distinction between bootstrap and xwiki variables in LESS files.
XE-1404: Switch to Flamingo Skin by default.
XWIKI-10212: Implement a (Color) Theme Application for Flamingo.

* First integration just by changing XWikiPreferences to also accept FlamingoTheme classes.