First round of code cleanups:

 - all instances of "vobj" have been renamed to "valobj"
 - class Debugger::Formatting has been renamed to DataVisualization (defined in FormatManager.h/cpp)
   The interface to this class has not changed
 - FormatCategory now uses ConstString's as keys to the navigators instead of repeatedly casting
   from ConstString to const char* and back all the time
   Next step is making the same happen for categories themselves
 - category gnu-libstdc++ is defined in the constructor for a FormatManager
   The source code for it is defined in gnu_libstdcpp.py, drawn from examples/synthetic at compile time
   All references to previous 'osxcpp' name have been removed from both code and file names
Functional changes:
 - the name of the option to use a summary string for 'type summary add' has changed from the previous --format-string
   to the new --summary-string. It is expected that the short option will change from -f to -s, and -s for --python-script
   will become -o

llvm-svn: 137886