ENH: robuster fileOperations splitProcessorPath

- robuster matching behaviour when encountering paths that themselves
  contain the word "processor" in them. For example,

    "/path/processor0generation2/case1/processor10/system"
    will now correctly match on processor10 instead of failing.

- use procRangeType for encapsulating the processor ranges

- provision for information of distributed vs non-distributed roots.
  The information is currently available from the initial setup, but
  can useful to access directly within fileOperation.

STYLE: modernize list iteration