moved to seperate header file

this typedef needed to move to a seperate header file so that it could
be referenced in other header files, as there is no forward declartions
for enums.
MPDatabaseVersion in own header

moved MPDatabaseVersion out to its own header and then added references
in other header files where appropriate.
Implemented path through which a file can be created.

MPDatabaseController and MPDatabaseDocument, needed new initializers to
properly support creating a new document.
Created view and supporting code to create a new file

Created a new view CreationView, and supporting ViewController. Design
closely mirrors that of opening an existing file. Added the
viewcontrollers to the main window controller. Creation of a new file
sort of works, the file is created and can be saved, but one can't add
anything to it.