Allow users to select multiple samples

Fix #374.

Signed-off-by: Don Naegely <naegelyd@gmail.com>
I went back and forth on this and then figured that they could get the sample labels from the filter display in the context panel if they need to see them. I was trying to avoid adding more display elements and further extending the dimensions of the modal by trying to display what could be a very long list of samples depending on who is using this and what they are attempting. I will add the sample labels since we're bound to get a request from a user soon enough...