added mediafiles to the website directory; contains logo, header, screenhots, icon, etc.
rework resource structure to better fit the installer (WIP)

- move resources to src/main/resources

- eliminate the System directory

- replace System.ini + SystemProperties.java with apache commons config (merge into main.properties)

- refactor any place where SystemProperties is used

- add generic method for opening URL via Desktop

- rename main.cfg -> main.properties

- move help files to resources

- move documents to resources

- move all images to resources

- move default project to resources (ProjectTemplates)

- move other *.properties files to resources/config

- replace opening of external URL with Utilities.OpenURL

- remove possibility to use simple UI

- remove remaining update checker

- add HTML based installer panel (using src/main/resources/installer_readme.html)

- remove first and second panel