IO Graph should not be limited to 250k points (NUM_IO_ITEMS)

This issue was migrated from bug 8460 in our old bug tracker.

Original bug information:

Reporter: Cristian Constantin
Status: CONFIRMED
Product: Wireshark
Component: Qt UI
OS: All
Platform: All
Version: Git

Attachments:

gdb.txt: gdb trace for the dumped core (values for idx and it are shown as well)