Fix for TextBoxes and OpenGLSample crash

TextBox Fix:
- When moving the caret or adding characters that exceed the textbox's visible space, the text did not change its position, although the carat did.
- Adds empty PostLayout() in TextBox class to avoid Label's PostLayout from being called. Otherwise the text's position will always be set to a fixed position defined by the alignment.

OpenGLSample Crash Fix:
- Order of operations was causing the crash. The OpenGL renderer was being deleted before the TexturedBase skin, which depended on it.
- Changes TexturedBase skin to a pointer, allowing it to be deleted before the OpenGL renderer.

Misc changes:
- Removed extraneous semicolon in TextBox::MakeCaratVisible()
- Added newline in TextBox.cpp and OpenGLSample.cpp to avoid GNU compiler warnings