Root find package version

[guiguem]

If we change find_package(root 6.00) into find_package(root 7.00) in the main CMakeLists.txt, cmake will print:

-- Building submodule Cicada at /Users/mguigue/Work/Project8/SourceTree/katydid/Cicada
-- Found ROOT: /usr/local/bin/root-config (Required is at least version "7.00") 

and will go on as if everything was fine.

Found this "issue" in another project, but this should apply in every repo where we have root package...
Very low priority, but this might hide some issues with other packages...

[guiguem]

A solution is to add

if (${ROOT_VERSION} VERSION_LESS 6.00)
    MESSAGE( FATAL_ERROR "Root version (${ROOT_VERSION}) smaller than 6.00")
endif()

in the FindROOT.cmake right after the ROOT_VERSION definition