Fixed main module for execution without a specified target.
Renamed BaseCompiler, etc. to AbstractCompiler, etc. Added exception "NoTargetException" which is raised by the main module when no target is specified _and_ no target is found in the main make-module. Added shutil.py which contains a function remove_files() for conveniently building clean() methods on targets.
Added the make.compiler.rebuildvalidator module and implemented it into the BaseCCompilation class.
Replaced the default rebuild validator for the BaseCCompilation with CIncludeRebuildValidator. The interface for BaseCompilation has changed to always accept the compiler as an input parameter.
Removed the example project
The PYMAKEPATH environment variable is now used in the make.__main__ module to determine additionial search paths for Pyhton make-modules.
Adjusted imports in files, relative if possible.
Revert "Adjusted imports in files, relative if possible."

This reverts commit 6ee394fe901ae9417c294a34369e2f91bf07972f.
Imported important classes into the make.__init__ module.
Fixed error with missing name
Added options to the Session
Session options can now be specified via command-line
Added wrapper class for constantly defining the tolerable argument for getter methods in the make.session.Optons instance.
Imported more classes in make.__init__
Compilers now also have an Options instance.
Added Options.merge()
Added Sequence and CompoundGenerator classes. All AbstractFilenameGenerators now support adding resulting in a CompoundGenerator instance.
Added PathNormalizer.move_to()
Added Target class, it will be filled with more convenient functionality in the future.
Added Attributor class