Numbers in sheetnames should be increased when dragging to extend formula

[alvarezguille]

Originally reported in forum https://vaadin.com/forum/#!/thread/16976822

Can be reproduced in demo.vaadin.com/spreadsheet

• Open styling demo and create a second sheet
• Set a cell value to ='Sheet2'!D2
• Use the bottom-right green square to drag fill the following cells with the formula.

Expected behavior:

• Following cell has formula ='Sheet2'!D3

Current behavior:

• Following cell has formula ='Sheet3'!D3