Merge pull request #66 from stoewer/master

Add missing virtual dtors to classes in nix::base
rename of delete methods in file*
rename of delete methods in section*
rename of delete methods in Property*
rename delete methods in Source* and Block* files
rename delete methods in DataArray* files
rename of delete methods in SimpleTag* files
Merge pull request #68 from jgrewe/rename_delete_methods

All OK (closes #67)
removed old TestEntityWithMetadata
add new test for base entity class
new test for EntityWithMetadata
activate new tests
removed old TestEntityWithSources
add new tests for EntityWithSources
update with new Test
rename removeSource to deleteSource in TestEntityWithMetadata
FindCppUnit.cmake: Add CPPUNIT_ROOT env var support

With this change it is possible to specify the location of the
cppunit framework.
[CMake] fix cppunit include dir variable (typo)

Actually pick up the correct location set by cmake for the cppunit
framework.
[CMake] only set (gcc/clang) compiler flags on !win32
Platform.hpp: new header for platform specific things

Currently only Win32 specific things are defined here