Fix the value extraction of long doubles in input.

Allow "long double" in the type determination for numeric literals.
Implement G__atolf (doesn't exist on std C++).
Remove not compiled and non-standard G__atodouble.


git-svn-id: http://root.cern.ch/svn/root/trunk@29614 27541ba8-7e3a-0410-8455-c3a389f83636