Filters: superclass for filters and some standard filters
Block: use new filters in method simpleTags()
Merge pull request #65 from stoewer/master

A superclass for filters (closes #64)

LGTO. Test also locally.
Add missing virtual dtors to classes in nix::base

This should fix #32
Further my IDE auromatically corrected some indentions
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)
Sync with master

Merge branch 'master' into win32
Conflicts:
	include/nix/Section.hpp