ibtop: Add name to ibtop_node structure

The name stored in ibtop_node is a shortened version of the
nodedescr in ibnd_node with the "HCA-1"/"HCA-2" or "mxl4_0"
removed.
ibtop: Detect and handle overflows/resets

When counters overflow or are resetted the computed bandwidth
will be negative. This commit adds code to detect this and
handle appropriately.
ibtop: Improve visualization

This commit adds the following improvements to the curses gui:
 - colored bars
 - use shortened/clean names
 - add information about percentage of peak