Improve tear down in case of interpreter static object holding pointer to object in TFiles.

We need to first Close the file before deleting the interpreter object,
otherwise the script:

   auto f = TFile::Open(filename,"RECREATE");
   TH1F h(...);
   h.Fill();
   // etc...
   .q

would result in an 'empty' file.

However, when closing the file, we can not delete the object its own and some interpreter
static object (for example a MakeClass skeleton) might hold pointer to those objects.

To resolve this, we introduce a new flag to TDirectory/TDirectoryFile/TFile Close ("nodelete")
that will write the data in to the physical file but will not remove the object from memory.

valgrind --suppressions=/opt/build/root_builds/rootcling.cmake/etc/valgrind-root.supp root.exe -b -l -q execLHEF.C
==6337== Memcheck, a memory error detector
==6337== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==6337== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==6337== Command: root.exe -b -l -q execLHEF.C
==6337==

Processing execLHEF.C...
direct
Warning in <TClass::Init>: no dictionary for class TRootLHEFEvent is available
Warning in <TClass::Init>: no dictionary for class TRootWeight is available
Warning in <TClass::Init>: no dictionary for class TRootLHEFParticle is available
Warning in <TClass::Init>: no dictionary for class TSortableObject is available
all=79618 zero=60000 low=9599 high=10019
reader
all=79618 zero=60000 low=9599 high=10019
legacySelector
Info in <TTreePlayer::MakeClass>: Files: lhef_leg_sel_gen.h and lhef_leg_sel_gen.C generated from TTree: LHEF
all=79618 zero=60000 low=9599 high=10019
selector
all=79618 zero=60000 low=9599 high=10019
makeClass
Info in <TTreePlayer::MakeClass>: Files: lhef_mc_gen.h and lhef_mc_gen.C generated from TTree: LHEF
all=79618 zero=60000 low=9599 high=10019
(int) 0
==6337== Invalid read of size 8
==6337==    at 0x1636165F: TTree::GetCurrentFile() const (TTree.cxx:5247)
==6337==    by 0x405F343: ???
==6337==    by 0x405E6DB: ???
==6337==    by 0x405E6AB: ???
==6337==    by 0x911919A: cling::IncrementalExecutor::runAndRemoveStaticDestructors(cling::Transaction*) (in /mnt/vdb/lsf/workspace/root-pullrequests-build/build/lib/libCling.so)
==6337==    by 0x90C7A3D: cling::Interpreter::runAndRemoveStaticDestructors() (in /mnt/vdb/lsf/workspace/root-pullrequests-build/build/lib/libCling.so)
==6337==    by 0x8FB13E2: TCling::ResetGlobals() (TCling.cxx:3237)
==6337==    by 0x52C4915: TROOT::EndOfProcessCleanups() (TROOT.cxx:1193)
==6337==    by 0x54CC89F: TUnixSystem::Exit(int, bool) (TUnixSystem.cxx:2153)
==6337==    by 0x5361A5B: TApplication::Terminate(int) (TApplication.cxx:1281)
==6337==    by 0x4E52AE2: TRint::Terminate(int) (TRint.cxx:686)
==6337==    by 0x4E5183E: TRint::Run(bool) (TRint.cxx:437)
==6337==  Address 0x11387c40 is 336 bytes inside a block of size 696 free'd
==6337==    at 0x4C2C171: operator delete(void*) (vg_replace_malloc.c:575)
==6337==    by 0x53BC849: TStorage::ObjectDealloc(void*) (TStorage.cxx:362)
==6337==    by 0x53A2A9A: TObject::operator delete(void*) (TObject.cxx:988)
==6337==    by 0x16353FA7: TTree::~TTree() (TTree.cxx:958)
==6337==    by 0x5416C48: TCollection::GarbageCollect(TObject*) (TCollection.cxx:734)
==6337==    by 0x541F3B6: TList::Delete(char const*) (TList.cxx:534)
==6337==    by 0x5419B66: THashList::Delete(char const*) (THashList.cxx:215)
==6337==    by 0x82D03C9: TDirectoryFile::Close(char const*) (TDirectoryFile.cxx:556)
==6337==    by 0x82E1049: TFile::Close(char const*) (TFile.cxx:942)
==6337==    by 0x52C411F: (anonymous namespace)::R__ListSlowClose(TList*) (TROOT.cxx:1092)
==6337==    by 0x52C4220: TROOT::CloseFiles() (TROOT.cxx:1113)
==6337==    by 0x52C48EF: TROOT::EndOfProcessCleanups() (TROOT.cxx:1190)
==6337==  Block was alloc'd at
==6337==    at 0x4C2B145: operator new(unsigned long) (vg_replace_malloc.c:333)
==6337==    by 0x53BC7DD: TStorage::ObjectAlloc(unsigned long) (TStorage.cxx:330)
==6337==    by 0x4E4F165: TObject::operator new(unsigned long) (TObject.h:152)
==6337==    by 0x162D5267: ROOT::new_TTree(void*) (G__Tree.cxx:3940)
==6337==    by 0x54669D2: TClass::New(TClass::ENewType, bool) const (TClass.cxx:4777)
==6337==    by 0x8329330: TKey::ReadObjectAny(TClass const*) (TKey.cxx:1058)
==6337==    by 0x82D1FB0: TDirectoryFile::GetObjectChecked(char const*, TClass const*) (TDirectoryFile.cxx:1044)
==6337==    by 0x16340AC4: void TDirectoryFile::GetObject<TTree>(char const*, TTree*&) (TDirectoryFile.h:80)
==6337==    by 0x405F27F: ???
==6337==    by 0x405E5F3: ???
==6337==    by 0x405E5BB: ???
==6337==    by 0x405E01D: ???
==6337==
==6337==