Added new cmake variable SHARED_LIBRARY. By default is on.
When it is off QCA library, plugins, tools, examples and unittests
will be built as static. Also if is used static Qt plugins will be
built as static. Tested with Qt4.
QCA_LIB_SUFFIX intended to replace workaround
3 major version. For building for Qt5 can be used
-DQCA_LIB_SUFFIX=qt5 for example. Result will be
named libqca2-qt5.so.2.0.3 library for Linux.
Also this suffix will be applied for qca2 pkg config file,
qcatool2 binary and qcatool2 manpage.
I hope that is a good way to resolve the building conflict
against qt4 and qt5.
