Bugfix in event filtering

* Fireworks/Core/interface/FWRepresentationInfo.h
  * Initialize m_requiresFF in full ctor.
* Fireworks/Core/src/FWFileEntry.cc
  * Use proper edm::Wrapper typeid when asking fwlite::Event for branch name (by Chris). This fixes a bug that basically made event content and navigation random after one tried to enable filters.
  * Cleanup surrounding code:
    * Use a map to store previous branch addresses.
    * Only do branch-name query and regex_replace for matching collections.