[BUG] FsCells with row#/col# 0/0 are invalid, yet ctor creates them

[omaus]

Describe the bug
When creating FsCells with the constructor and not specifying the address, they are given the location row 0, column 0. This is not valid.

To Reproduce
Steps to reproduce the behavior:
1.

#r "nuget: FsSpreadsheet"
#r "nuget: FsSpreadsheet.ExcelIO"

open FsSpreadsheet
open FsSpreadsheet.ExcelIO

let wb = new FsWorkbook()
FsWorkbook.initWorksheet "test" wb
let ws = wb.GetWorksheets().Head

let cell1 = FsCell("test")
ws.CellCollection.Add [cell1]

FsWorkbook.toFile "test.xlsx" wb

2. Open in MS Excel, see error

Expected behavior
Should initiate with address row 1, col 1.