Original (read from file) comments can be accessed by pkthdr->opt_comment
Keep user comments in seperated BST, add new method for epan session to get it.
svn path=/trunk/; revision=51090
Remove ->prev_cap, for testing purpose also replace ->prev_dis with number of previously displayed frame number.
This patch reduce size of frame_data by 8B (amd64)
This is what (I think) was suggested by Guy in comment 13 (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5821#c13)
svn path=/trunk/; revision=50765