Massive enumeration name changes: a number of enums in ValueObject were not...

Massive enumeration name changes: a number of enums in ValueObject were not following the naming pattern
Changes to synthetic children:
 - the update(self): function can now (optionally) return a value - if it returns boolean value True, ValueObjectSyntheticFilter will not clear its caches across stop-points
   this should allow better performance for Python-based synthetic children when one can be sure that the child ValueObjects have not changed
 - making a difference between a synthetic VO and a VO with a synthetic value: now a ValueObjectSyntheticFilter will not return itself as its own synthetic value, but will (correctly)
   claim to itself be synthetic
 - cleared up the internal synthetic children architecture to make a more consistent use of pointers and references instead of shared pointers when possible
 - major cleanup of unnecessary #include, data and functions in ValueObjectSyntheticFilter itself
 - removed the SyntheticValueType enum and replaced it with a plain boolean (to which it was equivalent in the first place)
Some clean ups to the summary generation code
Centralized the code that clears out user-visible strings and data in ValueObject
More efficient summaries for libc++ containers

llvm-svn: 153061