TYPO3 Core

Allow to assign lang attribute to elements.

1. Two new toolbar elements: language (drop-down list of languages) and showlanguagemarks (toggle button)
2. Language markup may be done with lang or xml:lang attribute or both.
3. Showing language marks is done through css attribute selector and will not work when the xml:lang attribute is used alone.
4. The language marking drop-down list is also available in the image, table/column/row/cell and acronym/abbreviation dialogues
5. Acronym/abbreviation table has additional language property used, when set, as default language mark on the abbr/acronym element
6. Display of the language attribute value, if any, in the status bar is as: element[language-code]
7. Page TSConfig properties are:
RTE.default.buttons.language.items = list-of-language-iso-codes
RTE.default.buttons.language.prefixLabelWithCode = boolean
RTE.default.buttons.language.postfixLabelWithCode = boolean
RTE.default.buttons.language.useLangAttribute = boolean
RTE.default.buttons.language.useXmlLangAttribute = boolean
8. Localization of language labels in the drop-down list is obtained from localization extensions of Static Info Tables.
(issue imported from #M10182)