convertor.py moved to datastructures/

Bump #26.
Added new structure SemanticInfo to the alephrecord.py.

Bump #26.
Added docstrings to alephrecord. SemanticInfo is now parsed automatically.

Bump #26.
SemanticInfo structure moved from AlephRecord to own module.

This is because cyclic imports doesn't allows to have it there.

Bump #26.
Added documentation for semanticinfo.py.

Bump #26.
convertor.py can now parse hasAcquisitionFields.

Bump #26.
Added docstring to toSemanticInfo(). Fixed docstrings of toEPublication().

Bump #26.
Small change in DocumentQuery to reflect changes in AlephRecord building.
Fixed test suite. All tests passed.

Fixed #26.
Version 1.5.2.