Make cannot deal with 'export *', they have to be escaped and fixed later on.

This is the recommended way of using the modules feature and should pave our way
of enabling -fmodules-local-submodules-visibility mode.

There are still some issues when building the C++ modules implicitly from ObjC++
context.

Our two build systems can generate almost entirely a modulemap file laying out
one module per library. Due to some non-modular implementation in ROOT's core we
still need to treat some header files specially.

This patch appends modular header files to the modulemap while skipping the
predefined ones. Configure-make relates all headers that are installed in
$ROOTSYS/include to their library whereas relates only headers which are part of
library's dictionary.

Remove outdated or useless 'TODO's.

Some constants are deprecated starting from 10.11.

CGGradientCreateWithColorComponents accepts CGFloat as parameter,
which can be either double or float. TGColorGradient works with Double_t.
Make it work with CGFloat == float.

rootcling will write out ROOT files; that does not work for libCore and RIO
which instead use rootcling_tmp.
All other libraries use rootcling -rootbuild.
Rename ROOTCLINGTMP to ROOTCLINGSTAGE1; rootcling -rootbuild is ROOTCLINGSTAGE2.

ascii string is not ascii anymore and must be "encoded",
otherwise I have a metric for a wrong symbol.
Take care of multiple runs in CTLine (can never happen, but still ...).

very unfortunate in fact, so get rid of it.

must work with Cocoa coords, not ROOT's coordinates.

TRadialGradient and TLinearGradient are two new gradient fill options.

Thanks to Lorenzo.

now the library names in the rootmaps are sane.
In addition, the creation of the tmva and genvector dicts was
simplified.

- with anti-aliasing on non-retina displays lines look thick and semi-transparent.
Give a choice - if user wants them to look more "X11-like" (version with XQuartz).

X11-version just selects 2 instead - do the same (not to generate error
messages - e.g. piechart.C tutorial).