base/stl_utils: Use nullptr
base/stl_utils: Remove outdated Find() function

.at() provided by the STL gives the same semantics.
base/subprocess: Add a WaitForAll which waits for any child process to exit
jhm/naming: Add 'Contains' to TAbsBase
jhm/naming: Add two more convenience functions
base/path_utils: Use free() in GetCwd(), so it matches the malloc that the system uses
path_utils: Use unique_ptr but explicitly specify the deleter to be free()
Move std::swap to use ADL, the preferred method for C++11
base/thrower: Allow hierarchies to be built with DEFINE_ERROR
base/pos: Mark swap() noexcept
jhm/naming: Use std::algorithms more for ends_with per mpark's suggestion
base/demangle: Modernize/rewrite demangler interface
base/stl_utils: Remove unused include
base/json: Add a simple Read() which reads in a whole json file.
base/json: Eliminate some unnecessary copies (Force move of everything instead)
base/json: Include what was found as well as what is expected.
base/json: Match exactly what is asked for

Before we greedily matched anything which was not whitespace. So we'd read in commas after exact matches, for instance "true,".
base/json: Better error message
base/json: Add some utilities for mutating in place
base/json: Include filename when we error inside a file