Bugfix: mixed case in interface name on HP

In some version of the HP switch software, the aggregate
interfaces "Trk1" is configured in lowercase as in:

	trunk A1,B1 trk1 trunk

In other parts of the configuration, it is referenced as interface "Trk1".

We normalize the interface name in Title Case systematically.
Support for irb interface on EX4300

A new "integrated routing and bridging interface" has been introduced
: it behaves like the former vlan interface (including the l3-interface
statement).