#388 ESCET runtime launch configuration improvements

We now have two launch configurations:

• escet-dev-runtime.launch works as the one we had before (that was named escet-product.launch before). It makes all workspace plugins available in the runtime.
• escet-product.launch now really launches the product. It for instance no longer makes plugins available that are not contained (directly or indirectly) in the ESCET product features. This more faithfully resembles the product.
• The working directory names have been changed. You may want to change your existing working directory runtime-product-escet to runtime-escet-product, for it to work with the new escet-product.launch launch configuration.
• See the individual commits for more information.
• See issue #388 (closed) for more information, including links to Eclipse launch configuration changes that we're adopting here.

Closes #388 (closed)