babeld: Update to 1.5.1
babeld: Generate a configuration file instead of passing cmdline arguments

This is the first step toward fixing issue #33.

This still lacks some features:

- no support for "ignore" options
- no backward compatibility for option names
- no support for default interface options
babeld: Print an error when startup fails
babeld: Handle ignore options
babeld: Take interface name from "option ifname"

Previously, we were using the name of the section as the interface name,
but this has several drawbacks:

- no "-" or other special characters are allowed in a section name,
  preventing some physical interface names to be specified this way
  (e.g. "tun-topeka" would not work)
- it is harder to support default interface options (no interface name)

This change is not backward compatible, but a later commit will fix that.
babeld: Support default interface configuration

When a "section interface" does not have a "option ifname", all its
options are used as default interface options.
babeld: Update configuration file for new syntax
babeld: Backward compatibility with old config files

This allows to use the old syntax "config interface foo" for specifying an
interface.  The new syntax ("option ifname foo") takes precedence.

Also, old option names for the "general" section are translated
accordingly.  Exceptions are:

- 'hello_interval' and 'wired_hello_interval', which are now interface-specific;
- 'conf_file', since /etc/babeld.conf is now always used;

which are simply ignored.

Beware, the syntax for the 'diversity' option is not backward compatible.
Merge pull request #47 from zorun/babeld_configfile

Updates to babeld



This patchset:
- fixes #33 by generating a configuration file for babeld
- introduces a slightly different syntax for specfiying interfaces (backward-compatible)
- allows to use any option, as long as it's supported by babeld (i.e. valid options are not hardcoded in the init script anymore, all options are simply passed to babeld)

It is mostly backward-compatible, with a few caveats.

Thanks to Baptiste Jonglez.