Make insert functions work 100% correctly for complex types

[trzysiek]

Probably very low priority.

Right now the test below doesn't pass, as we don't handle complex types like Arrays of Tuples 100% correctly.
Same thing probably applies to a couple other functions which have very similar structure, it'd be good to check them as well.

func TestRemoveNonSchemaFields_Arrays(t *testing.T) {
	insertQueryMap := SchemaMap{
		"array": []interface{}{
			SchemaMap{
				"a": "avalue",
				"c": "cvalue",
			},
		},
	}
	table := &Table{
		Cols: map[string]*Column{
			"array": {
				Name: "array",
				Type: CompoundType{
					Name: "Array", BaseType: MultiValueType{
						Name: "Tuple",
						Cols: []*Column{
							{
								Name: "a",
								Type: NewBaseType("String"),
							},
							{
								Name: "b",
								Type: NewBaseType("String"),
							},
						},
					},
				},
			},
		},
	}

	afterRemovalMap := RemoveNonSchemaFields(insertQueryMap, table)
	pp.Println(afterRemovalMap)
	_, ok := afterRemovalMap["array"].([]interface{})[0].(SchemaMap)["c"]
	assert.False(t, ok)
}