Add settings to be imported into Eclipse

This should drastically simplify the initial setup.
These settings include:
* the target platform
* the workspace dir (is this still necessary?)
* the configuration of the warnings/errors/etc.
* the configuration of the Java formatter (from coding-conventions/eclipse-java-formatter.xml; has slightly changed; might be removed)
* the save actions (slightly more than before; also updated for new Java features)

The last two points modify our coding conventions (but also "force" everyone to use them), so existing source files might have to be modified.