- you can use a Python script to write a summary string for data-types, in one of
   three ways:
    -P option and typing the script a line at a time
    -s option and passing a one-line Python script
    -F option and passing the name of a Python function
   these options all work for the "type summary add" command
   your Python code (if provided through -P or -s) is wrapped in a function
   that accepts two parameters: valobj (a ValueObject) and dict (an LLDB
   internal dictionary object). if you use -F and give a function name,
   you're expected to define the function on your own and with the right
   prototype. your function, however defined, must return a Python string
 - test case for the Python summary feature
 - a few quirks:
  Python summaries cannot have names, and cannot use regex as type names
  both issues will be fixed ASAP
major redesign of type summary code:
 - type summary working with strings and type summary working with Python code
   are two classes, with a common base class SummaryFormat
 - SummaryFormat classes now are able to actively format objects rather than
   just aggregating data
 - cleaner code to print descriptions for summaries
the public API now exports a method to easily navigate a ValueObject hierarchy
New InputReaderEZ and PriorityPointerPair classes
Several minor fixes and improvements

llvm-svn: 135238