Moved Executer class implementation
Fixed Tree#from_path()
Implemented Tree to hash functionality
Changed the way a Entry gets parsed from a path
A day class should know its path, too
A Month should know its path
A Year should know its path
Added more metadata to hashes
Simplified hashes, so it is searchable
Skip ".." and "." directories here
Ensure that we dont do nil stuff here
Added Tree-Reading based on reader command filters

This patch adds the tree-reading based on the filters, named
reader_commands in here.
Fixed class path for class
Implemented Tree#all_entries
Removed debug output
If there are no reader commands, an empty array says "true"
We should remove nil entries right from the start
Fixed #from_path for Entry class
Fix: path checking in all #from_path overrides
pulled iteration up to point where it is required