KOffice libs uses so called CamelCase naming for all files in the libraries.
Example:  KoParagDia.cpp
Extensions are always .cpp and .h
We prefer one class per file.  This is to make the filename match the class, which
obviously does not work if there is more then one class in the file.
When there is a private class that is not used outside the file it's ok to have it
in the same file as another class.
