Renamed method addInputFieldAndButton

As there is no more button, the method does not need to have it in its
name.
Table View works with strange positioning

There is now a table view for displaying the results of the
calculations. This involved building a new bean called MoleculeModel.
The position of the shown table is still a bit strange and the columns
have not the right size.
Table colum width correct

The table columns have now the right width. The orientation of the table
is still strange.
Result table centred

I included the result table in a StackPane which can then be set to a
centred alignment.
Fixed main element mass of Ti

It should be 48 but was 46.
Fixed most frequent isotope mass of Ti