SQLite - Handle read-only files and multiple properties with same name in SQL command

[romicadascalescu]

SQLite throws exceptions late when user tries to insert/update/delete features. SQLite should expose read only in capabilities of the class (GetSupportsWrite/SetSupportsWrite). Handle SQL commands like "select Id as col1, Val+55 as col1 from tab" by generating new names for second name found. This change is meant for 3.6, however Version and Milestone is not updated yet.