Fix potential uncaught exception when reading files with PropertyList.

Change-Id: I4182704fa75b15a24c9d8dfceba02f40fc57928b
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Rename PropertyList API functions for better self-documentation.

Change-Id: I5435e99c68646340bf6a2608819cfaef31146646
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Add support for reading JSON plists in the PropertyList extension.

Change-Id: I3e0386373c2b4a530a9c4c77f5db6d84c7d0043f
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>