Reading from bytes / IOBuffer

[chris-b1]

I think it would be reasonable to support this directly as an overload of readxl / readxlsheet. Below is a example/workaround using xlrd directly.

using HTTP
using ExcelReaders

r = HTTP.get("url returning.xls")
wb = ExcelReaders.xlrd.open_workbook(; file_contents=r.body)
xf = ExcelReaders.ExcelFile(wb, "")
data = ExcelReaders.readxlsheet(xf, "Sheet1");