PackageDecorator: move some variables closer to their use sites

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
PackageDecorator: restructure

Prepare for the next patches

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
FileUtils: add toProjectResource

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Fix #577: include/exclude decorators incorrectly shown on test packages

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>