* Change THelix Ctor and doc

* use xyz instead of p

[ROOT-10302] Move glew to ROOT builtins (part 2)

Try to exclude as much as possible ${CMAKE_BUILD_DIR)/include from includes paths.
By this one much better control library dependencies - includes from other ROOT libraries not "visible" during the build.

Several generated files placed first to ${CMAKE_BUILD_DIR)/ginclude and then copied to include.

Dictionary generation still uses only ${CMAKE_BUILD_DIR)/include

Co-authored-by: Axel Naumann <Axel.Naumann@cern.ch>

- TEveTrackPropagator::IntersectPlane() remove assumption field is parallel to z.

- TEveTrackPropagator::HelixIntersectPlane() make calculation of intersect point
  more precise by using interpolation between last two points in the approach sequence.

- TEveMagField - clarify code, in-code comments and class documentation
  for TEveMagField.

- REveMagField - remove float versions of GetField() and claify code.
  Remove notice about non-standard magnetic field direction.

- REveTrackPropagator - invert sense of magnetic field so it is in line
  with standard definition.

- Make corresponding changes in eve and eve-7 tutorials.

In many places incldues are not required for the dictionary generation, 
therefore target_include_directories can be used 

Where not used 

Show wireframes in web viewer

Idea to implement only few methods for display of TGeoVolume 

Will be used to provide geo painter in web mode

Do not mix Bool_t and bool - although they are the same

Avoid unnecessary copy of object.
One can fully remove GetCName()/GetCTitle()