Feature: CMake support

This adds a CMakeLists.txt file
-------------------------------

An out-of-source build is recommended (CMake will generate some temporary files
which are ugly to have in the project tree).

### build process:
```bash
cmake <path to dob-project>
make
./dob
```
Attention: This will place the binary into the current build-folder instead of
the bin/ subdirectory inside the source tree.

The current ```Makefile``` can be removed (it is no longer used).  The
```Makefile``` did set some unnecessary variables. Their behaviour is
implemented but un-commented in the new CMakeLists.txt

The additional targets ```make new``` and ```make doc``` are implemented as well.