standardise method for updating sysctl.conf

[Jeff Johnson]

If I have a package to install and that package knows it needs a particular
kernel parameter setting there doesn't seem to be any standardised way of
maintaining /etc/sysctl.conf.

Cases I can think of are 'this feature needs to be on', 'this feature needs to
be off', 'this feature needs to be larger than 'n'' or 'this feature needs to
be smaller than 'n''.

There is an interesting question of what should be done between different
packages with conflicting requirements, whether a package could suggest a value
rather than needing it, and what happens when the package is uninstalled.

(I'm not sure this is the right place to suggest this - but it seemed the most
likely starting point).

Dave