Allow filtering total graphs by ifAlias, speed-up checks

Currently, total traffic filters keep comparing port data against the filters no matter if it was already found that it has to be ignored. This patch adds appropriate breaks in the code to speed this check up. This is done on each total graph generation, so the tall is not so small. Also, maybe interfaces which the total graph comprises, should be cached per-device in some way, so these checks are not executed each time.

Another functionality which our setup needed badly was a way to exclude the root trunk interface on a server using tagged VLANs only, from the total graph. Before that, the total graph actually represented twice the actual bandwidth, because it included both the root interface (e.g. eth0), and the VLAN subifs (e.g. eth0.1, eth0.2, eth0.3). By allowing to filter by ifAlias, we can now set a known alias to the trunk interfaces which need to be skipped (e.g. "TRUNK"), and then filter by it.