Tigon SQL changed interface setup

Changed interface setup and added query rewriting to comply with Tigon SQL compiler expectations

* Now each defined schema has an associated interface named `"<schemaName>"` ~~+ "s"~~ defined in file `<hostname>.ifq`
* ~~Each interface definition has a new field `<SubStream>` in `ifres.xml`~~
* ~~The Tigon SQL queries are re-written, such that each occurrence of `" " +  "<schemaName>" + " "` is replaced by `" [" + "<schemaName>" + "]." + "<schemaName>" + " "` to create the corresponding gsql file.~~
* The user is now expected to specify the interface as well as the schema while writing a Tigon SQL query
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