Fix build

[John-Colvin]

A whole bunch of minor things to keep this project working nicely with the latest dmd.

Important changes:

• dependency on the undead repo, in order to keep using {std,undead}.stream
• allowed warnings when building, because the ragel generated code does a lot of unreachable breaks.

[lomereiter]

Thanks for keeping this up to date! I've just sent you an invite to the organization.

[John-Colvin]

Cheers, I'd be happy to join although I can't promise to be very active. I'm not actually a user of BioD, this PR was actually prompted by a post by @biocyberman in https://gitter.im/DlangScience/public who was having trouble with it. As is often the case, fixing it looked like about the same amount of work as explaining how to fix it to someone else. I'm unlikely to be much use in the actual bioinformatics side (I'm a physicist), but I'm always happy to help with D-related problems, especially in open source scientific libraries.

P.S. Unless there's a reason not to, it would be useful to make a new release for code.dlang.org (and therefore most dub users) to use.

[biocyberman]

Wow! @John-Colvin You are my hero :)