[Babel-users] v4-over-v6 implementation

[Théophile Bastian]

> Check the kernel version number by default.  Allows a user to override the
> decision in the config file.
> 
> That's what we do with source-specific routing, and we've had no complaints.
> See kernel.c line 114 and babeld.c line 171.

I've implemented that this morning in branch `tbastian/v4ov6-detect` in 
my fork, here:
   https://github.com/tobast/babeld/tree/tbastian/v4ov6-detect


If it looks good to you, I can merge this onto my working branch for 
v4-over-v6, to include this in PR !56.

-- 
Théophile Bastian