Fix hiding the 'say' bubble WRT number formatting

When checking whether to hide the speech bubble, test if this block is the block that originally displayed the bubble rather than testing to see if the text matches. This avoids problems due to differences in text formatting or changes in a reporter's value.
Use GestureHandler as source for bubbles it creates

Shane explained that it would make more sense to use the GestureHandler
as the source for these particular TalkBubble instances.
Merge pull request #251 from LLK/bubble_hide_fix

Fix hiding the 'say' bubble WRT number formatting