Moved Dollar to subdirectory

Trying to make the project build correctly with GUI, created library
Dollar and moved it to Dollar subdirectory.
Changed directory structure

Moved source file to root src directory and made appropriate changes in
CMakeLists.txt to build it.
Reason: fewer CMakeLists.txt files, all source in one place, possiblity
of easier use of classes.
Using Dollar and BoardSample in main()

Added some instances of Dollar and BoardSample to check if it runs.
Fucking nailed it, finally Qt5 GUI works and it seems that I know how to
make this cmake build and link properly.