- Sometimes an extra point appeared in the center of a TGraph2D plot (when drawn with markers)
  The problem was mentioned here: http://root.cern.ch/phpBB3/viewtopic.php?f=3&t=18787&start=15
- Better manage the attributes reset when going from a markers representation to an other (P, P0, PCOL).
The hollow fill style was not rendered correctly (https://sft.its.cern.ch/jira/browse/ROOT-6841)
Disable Vc warnings on Windows.
Add protections at zoom limits.
Add missing lock to  TDataMember::Property
Add missing lock in TClass::IgnoreTObjectStreamer

Conflicts:
	core/meta/src/TClass.cxx
Remove obsolete code
For debugging make 'error' fatal
Avoid unnecessary recursion of BuildOld (and co) for emulated class
Add comment on suspicious (thread-safety wise) part of the code

Conflicts:
	io/io/src/TBufferFile.cxx
make error fatal for debugging
Extend reach of error message
Remove (now) redundant (useless) work.

IsCompiled() means that Build() or BuildOld() has been called.
Add atomic IsCompiled

Conflicts:
	core/meta/src/TVirtualStreamerInfo.cxx
	io/io/src/TStreamerInfo.cxx
Add missing lock in TStreamerInfo::Clear
Add progress comment
TVirtualStreamerInfo's IsBuilt and IsCompiled were almost the same, merge them.

We now consistently use IsCompiled as the sole spelling (IsBuilt is kept for backward compatibility)
Separate semantic of fIsBuilt and recursion prevention
typos
Clarify the different between IsBuilt and IsCompiled.

Separate again the value of IsBuilt() and IsCompiled()