Synthesize throwing of exception to handle the null deref.
Add forgotten to commit file.
Add missing header method declarations.
Use default cling style for naming classes.
Add base class for the interpreter's runtime exceptions.
Handle the default interpreter's runtime exception.
Commit Interpreter.cpp with dumpLookupTable() function not working yet.

This will be fully operational after the LLVM/Clang update.
Commit of storeState/compareState that now print lookup table
and included files

Implementation of .files moved in the Interpreter.cpp

storeState now calls three functions: dumpAST(), dumpLookup(), printIncludedFiles().
compareState now calls three functions: compareAST(), compareLookup(), compareIncludedFiles().
It's working for the included files and the AST, and it needs a new patch for
being able to dump the lookup tables (we cannot use dumpLookups() for the moment).
Remove the unused code.
Improve the look&feel of the exception classes.
Handle better the exceptions.
Don't use local type as template argument.
fix to pass search path for alternative gcc compiler and toolchain (ROOT-5384).
fine tune the alternative gcc include paths.