- Do not hard-code base path for future AJAX compatibility
- Add support for empty lists

- Fixes problems related to symlinks.

- In smaller screen sizes, display a button to expand the sidebar instead of having a wide border.

- Also begin checking a root /xsl directory in preparation for possible future reorganization away from modules.

- Old ID-based method was based on lack of confidence and added unnecessary complexity.
- Removing dependency on IDs will allow future simplification of the browse handler.

- Inspired by Ere Maijala's work on #1268.

- Work done by Agnès Manneheut

- Replaces previous feedback system in a backward-compatible way.

- Fixes Java 9/10 compatibility issues.

- Without the explicit sync folder ownership option, Vagrant 2.2.0 fails to create the "vendor/" directory when when running `vagrant up` the first time.

- Relying on APPLICATION_ENV is simpler.

Otherwise Zend\Session\Config\SessionConfig::setStorageOption() throws an exception when it tries to call ini_set with session-specific settings. This would have happened at least when creating a \Zend\Session\Container.

Add timestamps to static image urls like is already done for js and css files so that images can be cached without risk of missing any updates.

- This allows embedding to work more consistently, even though the user experience is not the best.