Re-enabled a lot of tests

src/esqlite3_nif.erl

@@ -27,6 +27,7 @@
     last_insert_rowid/1,
     changes/1,
 
+    exec/2,
     prepare/3,
 
     column_names/1,
@@ -97,6 +98,16 @@ open(_Filename) ->
 close(_Db) ->
     erlang:nif_error(nif_library_not_loaded).
 
+%% @doc Execute a sql statement
+%%
+-spec exec(Connection, Sql) -> ExecResult 
+    when Connection :: esqlite3(),
+         Sql :: sql(),
+         ExecResult :: ok | {error, _}.
+exec(_Connection, _Sql) ->
+    erlang:nif_error(nif_library_not_loaded).
+
+
 %% @doc Compile a sql statement. 
 %%
 -spec prepare(Connection, Sql, PrepareFlags) -> PrepareResult