Dedicated table options for Spider+ODBC

It would be nice to change the way how Spider ODBC tables are defined, from:

CREATE TABLE t1 (

  a INT NOT NULL

) ENGINE=SPIDER COMMENT='dsn "dsn", user "usr", password "pwd", table "t1", wrapper "odbc"';

to:

CREATE TABLE t1 (

 a INT NOT NULL

) ENGINE=SPIDER WRAPPER=ODBC TABNANE='t1' CONNECTION='DSN=dsn;UID=usr;PWD=pwd';

i.e. move the connection information from COMMENT to separate table options:

• WRAPPER - with TABLE_TYPE as an alias, for ConnectSE compatibility
• TABNAME - the remote table name. In case of remote databases that support schemas (e.g. PostgreSQL, Oracle), in addition to non-qualified names, e.g.: TABNAME='t1', it should also support qualified names, e.g. TABNAME='public.t1'.
• CONNECTION - in the format of ODBC's SQLDriverConnect. This format will allow to pass any kind of attributes (not only DSN, UID and PWD). For example, in case of SQLite, it can be:

  CONNECTION='Driver=SQLite3 ODBC Driver;Database=/tmp/test.sqlite3;NoWCHAR=yes'

Reasoning:

• Easier to migrate from ConnectSE. User will need just to fix ENGINE=Connect to ENGINE=Spider.
• Users might want to have "real" comments on their tables, e.g.:

  CREATE TABLE t1 (

  a INT NOT NULL

  ) ....

  COMMENT='This is my favourite ODBC table';

• More flexible about database-specific parameters (like Database in case of SQLite).
• This is the standard way to pass parameters to engines in MariaDB.