Add '@dynamic delegate' to RichTextEditorToolbar.m

[grgcombs]

RichTextEditorToolbar is a subclass of UIScrollView -- both define their own 'delegate' property and so we get compiler warnings due to assumptions about auto-synthesis of the property.

Please add the following to the RichTextEditorToolbar implementation:

@implementation RichTextEditorToolbar

@dynamic delegate;

// .....