Added file drag and drop support to open a new CSV file. Resolves #47. Also in this change, the start position of the Frm_CsvProperties form is now manually calculated instead of having the StartPosition property set to CenterParent. This is because for some reason, when dragging and dropping a file, the form's "StartPosition" property to CenterParent wasn't working - instead the CsvProperties form was appearing in the top, left of the screen.