[FEATURE] Add new Backtrace helper class.
[TASK] Add LICENSE.txt.
[TASK] Add extension icon.
[TASK] Only add styles when needed.
[TASK] Remove injection trait.
[TASK] Remove support for php7.
[TASK] Update .editorconfig.
[TASK] Update copyright notice.
[TASK] Update deprecated code.
[TASK] Update information about supported TYPO3 versions.