add DOC_SUBDIR to CMake-Vars
some distributions prefer %{name}-%{version} over
%{name}-%{soname_major} as doc-subdir.
disabled auto-gen of docs
INSTALL_DOCS=ON will no longer auto-gen the docs
added a warning to run "make docs" before "make install"
bumped up patch-version to 3.0.2
use SONAME from libyui instead of VERSION.cmake if plugin
updated ChangeLog
Merge pull request #40 from bjoern-esser/master

small improvements to buildtools