[TASK] Update Readme.md

[!!!][TASK] Switch from bower to yarn for JS dependencies

[BUGFIX] Use new namespace for FlexFormService

[TASK] Rename TSConfig files to .tsconfig

[TASK] Switch to lib.contentElement

[TASK] Change compatibility to TYPO3 8LTS and 9LTS

[TASK] Update personal information

[TASK] Adjust license comments

[TASK] Raise version to 1.2.0

[MERGE] Resolve Conflicts

[TASK] Move all TCA changes to TCA/Overides and remove ext_tables.php

[TASK] Make extension compatible with TYPO3 8LTS

[TASK] Adapt TYPO3 8LTS croping variants and sitch to FlexFormService

[TASK] Mention lib.contentElement in Readme.md

[BUGFIX] Add missing "mod." to preview code sample