The Eclipse and KDevelop generators set the VERBOSE environment variable to
TRUE in the project files, because they must be able to "see" the full
command lines and errors, otherwise they can't parse the errors. But the
VERBOSE env.var. also enables cmakes own verbose output, which can be quite
long. This commit introduces an environment variable CMAKE_NO_VERBOSE, which
when set disables cmake's verbose output also when VERBOSE is set. This
env.var is now set by both the Eclipse and the KDevelop generators.

Alex