Add tryGet<RecordName> versions of get<Record> calls

`tryGet<RecordName>`  returns Option types rather than raise exceptions.

For example:

    generateProcsForModels(MyDb, [ User ])

will now create both:

    proc getUser*(db: MyDb, id: string): User
    proc tryGetUser*(db: MyDb, id: string): Option[User]

fiber_orm.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "4.0.0"
+version       = "4.1.0"
 author        = "Jonathan Bernard"
 description   = "Lightweight Postgres ORM for Nim."
 license       = "GPL-3.0"