Text example: specify the base URL for the TextArea

So the TextArea looks inside its own resource file while
resolving relative urls used in the text.

Change-Id: Id67f3f3cbbd635e8defa04d97602e1e7b293874e
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Make import of QtQuick.Controls.Private consistent

Import QtQuick.Controls when QtQuick.Controls.Private
is imported.

Change-Id: I2c962b7310a74e0905e8cec08ee6563a5d98e9d7
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>