Remove ADORecordset_mssql::substr()
Remove ADORecordset_mssql::substr()

This method was introduced in 7d941967aa1b81d636f5b6e1f3549b2fc95248b9.

As mentioned in [1], since the function is already defined in
ADODB_mssql, it does not make sense to have it in the recordset too.
@mnewnham confirmed via Gitter [2] that it should be removed.

[1] https://github.com/ADOdb/ADOdb/commit/7d941967aa1b81d636f5b6e1f3549b2fc95248b9#commitcomment-17064111
[2] "Got completely lost with that substr in the recordset, that should
    not be their at all - If I put it into master it should be killed"

ipso/ADOdb,ipso/ADOdb