template 3.0.0 possibly add prot- folder for protocol type

[tgbugs]

may need a protocols- folder OR we may need a way to extend dataset_description related identifiers to allow a local name for the protocol, because we do need some accounting in metadata, OR only make protocols.xlsx required when a prot- folder is present ...

in combination with the updates to the manifest to allow mapping of spec- perf- and site- to a given file it seems reasonable to allow top level prot- folders, however we need to explore what other restrictions need to be placed on where and how it can be used

initial thinking is that if we require that prot- folders be unique then they can only appear at the top level of a hierarchy and cannot appear per subject, inside an individual subject a perf- should be used if such nesting is desired, if prot- folders do not have to be unique then we need work out the implications of how they would have to be interpreted

[tgbugs]

What do we do if multiple version of a protocol are used to collect data in the prot- folder?