ECMP is not enabled on BSD, where it is not supported by BIRD.

Several changes and bugfixes in Babel, namely:

- Exported route parameters stored directly in route table entry
- Exported non-babel routes no longer stored in per-entry route list
- Route update, selection and retraction simplified and fixed
- Route feasibility is evalualated per update and stored with route
- Unreachable route handling fixed, based on hold interval
- Added 'show babel routes' command

Overall, it fixes some issues with proper propagation of triggered
updates, making Babel convergence after topology change almost
instant.

Old behavior has several deficiencies compared to standard behavior
(no triggered updates for replies, no retransmissions, ...).

Babel TLV parsing code rejected IPv4 retractions without next-hop,
although next-hop is needed just for regular updates.

Also fix several minor bugs and add 'limit' option for k-out-of-j
link sensing strategy. Change default from 8-of-16 to 12-of-16.
Change IHU expiry factor from 1.5 to 3.5 (as in RFC 6126).

Note that recurrent timers are currently limited to ~1 hour.

Use '%t' in bsnprintf() for microsecond times (in btime) with variable
sub-second precision.

Date/time output (e.g. in logs, show commands) can use %f to specify
subsecond time. By default, millisecond precision is used in output.

The old timer interface is still kept, but implemented by new timers. The
plan is to switch from the old inteface to the new interface, then clean
it up.