Add new file.
Remove unused CXX11.
Remove spurrious space added in TClassEdit::ResolveTypedef

This solves ROOT-5778 by making sure that
 TClassEdit::ResolveTypedef("const std::string&")
and
 TClassEdit::ResolveTypedef("const std::string &")
returns "const std::string&"
lookup globally overloaded operators in std::__1 as well
Be more precise when comparing compilation and runtime libc++.

For instance XCode 5.1 braught a libc++ that was sufficiently different to cause havok
all over the place. Thus ABI_VERSION is clearly not enough.
special case for cout (backwards compatibility)
workaround relied on a bug ... and then the bug got fixed :)
The table of content on individual html chapters obscured the text.
Fix typo
Implement soft reset of the diagnostics engine.
Suppress warnings coming from system headers.
Don't recreate the diagnosic client, just set it to the tweaked instance.
Set the ignored diags before the driver does parse from args.

This allows the driver to override our custom diagnostics if the user wants any
special treatment.
Fwd declare the clang::DiagnosticsEngine.
Use better, more accurate include.
Reduce includes.
CXX consistency.
Do not leak the diagnostics engine.
Simplify.
Escape -x flags passed in as invocation.