Rename metadata -> storageFormats.

Rename the metadata sub-folder to storageFormats, as it was decided that there
should be special storage objects for all the data, not just the metadata and
the new name reflects this better.
storageFormats: Rename data -> event.

Rename a number of files so that the "data file" is now an "event file".
In this commit, the files are renamed without changing them, i.e. the
compilation is broken.
storageFormats: Port rename through files.

After the file renames in the last commit, implement the name change in
all the source files, which should make the compilation working again.
The files in the pyInterface still have to be renamed though, so two
more commits with renames coming.
pyInterface: Rename files.

As with the previous commits, rename the metadata subfolder to storageFormats
and change the file names to work with a "eventFile" instead of a "dataFile".
Compilation is broken in this commit and will be fixed in the next one.
Do final renames.

To the final propagation of the file renames from the previous commits.
Compilation should be fine again now.