Add a few recommendations from Sean

Author: quinnj

src/SQLite.jl

@@ -230,7 +230,7 @@ rollback(db) = execute!(db, "ROLLBACK TRANSACTION;")
 "rollback transaction or named savepoint"
 rollback(db, name) = execute!(db, "ROLLBACK TRANSACTION TO SAVEPOINT $(name);")
 
-"drop the SQLite table `table` from the database `db`; `ifexists=true` will not return an error if `table` doesn't exist"
+"drop the SQLite table `table` from the database `db`; `ifexists=true` will prevent an error being thrown if `table` doesn't exist"
 function drop!(db::DB,table::AbstractString;ifexists::Bool=false)
     exists = ifexists ? "if exists" : ""
     transaction(db) do

src/Sink.jl

@@ -1,6 +1,7 @@
 sqlitetype{T<:Integer}(::Type{T}) = "INT"
 sqlitetype{T<:AbstractFloat}(::Type{T}) = "REAL"
 sqlitetype{T<:AbstractString}(::Type{T}) = "TEXT"
+sqlitetype(::Type{NullType}) = "NULL"
 sqlitetype(x) = "BLOB"
 "SQLite.Sink implements the `Sink` interface in the `DataStreams` framework"
 type Sink <: Data.Sink # <: IO