Do not waste time on empty string.

In TCling::AutoParse, we use GetSplit which now always return the type's trail
even when it is empty.
Avoid unintentionally adding (empty) elements to the ClassesHeadersMap
Avoid strange escape sequences to please XCode generator.
Please also makefile
When autoloading from the interpreter, we also need to autoparse.

This is especially true for TClingCallbacks::InclusionDirective and parsing a header might lead to the
indirect request for autoparsing a related type which could lead to the parsing of header files that
requires types declared in the top most header (the one that induces the autoparsing) but this fails
because the 2nd inclusion of the header is ineffective (code guard are respected) but the 1st inclusion is
not finish.

This fixes root.exe -b -l -q stressShapes which lead to something like:

In file included from input_line_234:50:
/local2/pcanal/root_working/nightly/trunk/root/include/TGeoPatternFinder.h:89:65: error: member access into incomplete type 'TGeoVolume'
   TGeoNode           *GetNodeOffset(Int_t idiv) {return fVolume->GetNode(fDivIndex+idiv);}
                                                                ^
Fix a compiler warning
different check on the existence of gGeometry as it's not preloaded
Some more fixes to tutorials

did not import change in:
	tutorials/CMakeLists.txt
	tutorials/io/hadd.C
Finish the changes to silence warnings
Creation and installation of hsimple.root  (ROOT-6620)
Another warning
One plural is sufficient.
Add iterator interface for TTreeReader.

We want sequential reads, thus use a forward iterator.
The iterator does not really reference any data but the tree entry number
so return that as the deref-op. The same operator (also called from the
increment operators) sets its entry number in the associated TTreeReader.

This iterator is "C++14 safe" in that its past-end-iterator can be value
constructed and all past-end-iterators compare equal.
From Patricia: Several fixes in the GDML parser. GDML tag "fraction" now supported; GDML constants now supported; Empty world volume due to multiple GDLM files was fixed

(cherry picked from commit 5313dfc579cfeb7332024dbde568c7fbacb37f8b)
Do not fwd declare unnamed classes nor typedefs to them (ALICE).
Turn on C++11.
Generate hsimple.root as part of the build.
Anonymous types are now prefixed by "(".
Do not store PCMs for anonymous classes.
Do not select unnamed classes through typedefs.