Update internal version of freetype to 2.6.1 as requested here: https://sft.its.cern.ch/jira/browse/ROOT-7631

Fix issue with TGeoPainter and the new implementation of TFormula (see https://root.cern.ch/phpBB3/viewtopic.php?f=3&t=20555 ). Added geom tutorials that can run without GUI.

Avoid crash when accessing elements with empty vectors. Fix for ROOT-7740. Returns also now a Nan as in the case of Matrix

More investigation is needed about the failure seen for the  roottest-root-meta-autoloading-headerParsingOnDemand-FullheaderParsingOnDemand-libgen-build test.

This reverts commit 8decb9e1.

Due to the new way Apple builds python on 10.11 (El Capitan) each plugin
must specify where to find dependent libraries. This is done by
specifying the rpath using @loader_path (see man dyld) when creating
the plugins. In the past we provided this rpath specification only for
the executables but now for all plugins.

For each autoparse record to under which transaction it is being done. If this transaction is
rolled back, make sure to clear the caches that noted that this autoparsing had be done.

Y axis are now set to the lowest positive values of the graph. Previously a % of the
maximum was used which may hide some points like in the following example

{
   TGraph * gr = new TGraph(10);
   for (int i = 0;i<10;i++) gr->SetPoint(i,i,TMath::Exp(-10.0*i));
   for (int i = 5;i<10;i++) gr->SetPoint(i,i,0.);
   gr->Draw("apl");
   gr->SetMarkerStyle(20);
   gPad->SetLogy(true);
}

The problem was reported here: https://root.cern.ch/phpBB3/viewtopic.php?f=3&t=20484

- Formatting
- Spell check

Due to some internal changes in Cocoa, NSWindow object seems to be
'over-autoreleased' way to many times if we do not have any pools
on a pool stack except the top level one; it can happen then that
such 'deleted' window stays on screen after its widget was deleted (but
NSApplication/run loop still did not have a chance to drain a pool,
for example, during some heavy processing on a main thread).
This patch addresses this problem by:
  - using local autorelease pools
  - calling -orderOut: for a window if it's considered
    to be deleted (at least this will immediately remove it from screen).

When the default TApplication is replaced by a user provide TApplication, do not call EndOfProcessCleanups
and co. and thus do not delete TFiles, TSockets or TColors that have already been created.

Parts of this were accessed through redefining private/protected as public
which, besides of being a nasty hack, does not work with gcc-5.