Make releases semver compatible

This release is to make the project compatible with semver as requested here.

We shall start with v0.0.3 as there were a few old releases which predate this one.

MacVtap interface

This release cleans up some existing code and adds a new link interface: macvtap.

There is a small breaking change - renaming VlanDev and MacVlanDev to simply Dev in VlanOptions and MacVlanOptions.

All the other changes should not affect the package usage.

First release

This is the first tenus release. It will probably be very unstable. Let's hack on!