v0.9.4

This release contains a fix for towbootctl image: Generated images now always have a size that is a multiple of 512. This should fix problems when booting the generated image over the network.

In addition, towboot now emits better warnings and errors when kernels can't be loaded because the memory is already occupied.

It also contains various updates to dependencies.

This is basically 0.9.3, but with working modules.