Proposal: Add flexible version of getTables, and getTableTypes

[mpilgrem]

getTables :: Connection -> IO [String] provides results for ODBC table type TABLE. I found myself wanting the equivalent results for other ODBC table types, such as VIEW or SYSTEM TABLE.

Perhaps the library could be extended to include:

getTablesOfType :: Connection -> String -> IO [String]
getTableTypes :: Connection -> IO [String]

so that getTableTypes conn provides a list of the valid table types for conn and getTablesOfType conn "TABLE,VIEW,SYSTEM TABLE" (for example) gets the relevant table names of those types.

I have done that in a fork, by extending the constructor of data type Connection. Would it be of interest? If yes, I'll make a pull request.