Fix bug #101060: Editor not preserving MathText


git-svn-id: https://root.cern.ch/svn/root/trunk@49087 27541ba8-7e3a-0410-8455-c3a389f83636
From Mattias Mellert (#100973):
Fixing 2 issues. 
1. Using 

ruby -rrbconfig -e 'puts RbConfig::CONFIG["ruby_version"]' 

to extract the version of ruby being used is not reliable, and with the
ruby 2.0 in Fedora 19 it fails (an empty string is returned). A better
alternative is to use 

ruby -rrbconfig -e 'puts RbConfig::CONFIG["MAJOR"]' 
ruby -rrbconfig -e 'puts RbConfig::CONFIG["MINOR"]' 

instead. This also works with ruby 1.8 on RHEL 5 and 6. 

2. The RFLOAT_VALUE macro in ruby 2.0 resolves to an inlined function and
is therefore not a valid lvalue any more, and the address-of operator can
not be applied to it. The construct &RFLOAT_VALUE(...) is used in the
rr_parse_void function, which therefore no longer compiles. This function
is not called anywhere in the code, nor is it part of the modules public
interface since it is not listed in any installed header. So simply
removing this function makes the code compile again.


git-svn-id: https://root.cern.ch/svn/root/trunk@49089 27541ba8-7e3a-0410-8455-c3a389f83636