Typo3 10 (#74)
* [TASK] Remove variable
* [TASK] Rise version numbers
* [TASK] Migrate PATH_typo3 constant in PHP
* [TASK] Migrate version_compare conditions - remove support for older TYPO3 versions
* [TASK] Migrate PATH_site constant in PHP
* [TASK] Migrate getTSConfigVal() method for getting user settings
* [TASK] Migration URL generation for clear cache hook
* [TASK] Disable caching in enabled development mode
* [TASK] Optimize composer.json
* [TASK] Revert changes
* [TASK] Make dyncss branch typo10-3 installable with TYPO3 9
Co-authored-by: Thomas Deuling <info@coding.ms>
Co-authored-by: Thomas Deuling <1298841+tdeuling@users.noreply.github.com>
Co-authored-by: Christian Bülter <cbuelter@coding.ms>
