remove unnecessary headers and comments
use the standard accessor to set identifiers for files
move the object dictionary to QSLibrarian

Also removes the defaultSearchSet, since it would just contain the
dictionary’s values.

related to #1625
get existing objects from QSLibrarian
safer access to the object dictionary
turn `parent` into a property of QSObject

This eliminates a dependency on QSLibrarian.
eliminate findDuplicateOrRegisterID

As of dbe8512c31, objects will always be created with a "registered"
identifier.
fix a warning for the objectDictionary property
Revert "turn `parent` into a property of QSObject"

This reverts commit dfa6a62f7a9d93d3b15da946320f9c3eed11e5c8.
Merge branch 'master' into lookup
Merge pull request #1648 from quicksilver/lookup

fix the object dictionary