Support for new rmap file form. added + improvements

 * New rootmapfile format now supported: generate new rootmap files with the --newRmfFormat and -newRmfFormat flags in genreflex and rootcling respectively
 * rootcling and ACliC: new and old format treated transparently
 * Some global variables removed. Only gAutoLoads and gLibsNeeded remaining since used in RecordDeclCallBack. Thinking to a way to get rid also of those.
 * More elegant llvm::dyn_cast used for rtti instead of more verbose if (isa<..>...) ..  cast<...>..;
 * Minor cosmetic