Morpho

Currently only entire datapackages can be deleted. We need the ability to delete
data files and individual metadata modules.

1) Add a 'Delete Data...' to the Data menu for deleting data that is the current
entity. Add a dialog asking if only the data should be removed, or the data and
all associated metadata (i.e. the entire entity, attributes, physical info, etc.)

2) Add a 'Delete' button to each metadata display area so that the user can
delete selected metadata modules. May need to ask (or warn) about the
consequences of removing certain modules that have submodules.