Initial implementation of selection file input.

Initial implementation of selection file input.

- Add SelectionFileOption and related classes to implement an option
  that can be used to provide selections from a file.
- Add SelectionCollection::parseRequestedFromFile() to do the actual
  work.
- Add special handling for the option in command-line help to print it
  together with other selection options.
- Add tests.
- Removed support for specifying a selection option multiple times on
  the command line, since it is not clear how it should work together
  with the new option.
- Temporary exception safety fix for selection file input.
- Updated valgrind suppression rules for MacOS for some
  exception-handling stuff.

Initial implementation for IssueID #656.

Change-Id: Id4ddf545ec13986fa57dac42a8b1dc4075a42840