This class supports some functions of file system access as enhancement of the class java.io.File
independently of other classes of vishia packages, only based on Java standard.
Some methods helps a simple using of functionality for standard cases.
Note that the Java-7-Version supplies particular adequate functionalities in its java.nio.file package.
This functionality is not used here. This package was created before Java-7 was established.
Exception philosophy:
The java.io.file classes use the exception concept explicitly. Thats right if an exception is not the normal case.
But it is less practicable if the throwing of the exception is an answer of an expected situation
which should be though tested in any case.
Some methods of this class doesn't throw an exception if the success can be checked with a simple comparison
and it should be inquired in usual cases. For example
FileFunctions.getDirectory(File) returns the directory or null
if the input file is not existing. It does not throw a FileNotFoundException. The result is expected, the user
can do a null-check easily.