#250 Cmake: Combination of static and debug

[Michael Meidlinger]

Currently, there is no way to build the library as both static and in debugging mode. I see that static builds are more interesting for productive use rather than for debugging. However, the Installation instructions do not say that the cmake debugging and static flags are mutually exclusive. I attached a patch modifying CMakeLists.txt to introduce an addidtional target itpp_static_debug if both of these flags are set.