Update SphinxDB.GetColumns to use Sphinx's DESCRIBE output to build column definitions instead of delegating unconditionally to MySQL. The code issues `DESCRIBE <table>` and parses Field/Type/Properties (with case-insensitive lookup), sets sensible defaults (Nullable="YES", no primary key, Extra from Properties) and marks indexed fields as MUL. If DESCRIBE fails or returns no rows the implementation falls back to s.MySQLDB.GetColumns. Also add a logger import and a warning when DESCRIBE returns no columns.