[WIP] Separate core wolf files from the rest with SRCS_BASE and HDRS_BASE

I kind of organized the .h and .cpp fines in the src/CMakeFiles.txt so that:

• in HDRS_BASE and SRCS_BASE we have all files forming the wolf core
• in HDRS and SRCS we have all derived classes
• I also made or completed some groups, like SRCS_DATASSC