Remove unneeded static member decls; mark c'tor, d'tor as deleted.
Move CheckABICompatibility() to IncrParser; move funcs into unnamed namespace.

The IncrParser has the ability to check the stdlib that the interpreter sees,
versus what the compiler sees. Of course what we want to check is the
interpreter's stdlib - including any -I passed at the prompt. The other
advantage of this change is that system headers are now pulled from the PCH
if it exists (ROOT-6794)
Refactor diag of unresolved syms; also diagnose in getAddressOfGlobal().
Bring back old diag format.
Adapt to new Transform::Config::m_toSkip.
Survive failure in dyn expr building (ROOT-6824).
Silence warning. Keep the FIXME visible :-)
Show parsed (with open file handle?) versus deserialized.
Fix doc warning.
Give cling the LangOpts clang has.
Fix clang / cling LangOpt discrepency on Linux.
Fix doxygen warning.
Return 0 to signal missing symbols.
Memory error: getSpelling() returns a std::string (thanks, valgrind).
Ensure redecls are part of the chain when unloading (ROOT-6832).
Default to successful action (ROOT-6611).
Do not call and action a failure if it is not handled here (ROOT-6611).