The review of std.hash package

[Piotr Szturmaj]

Johannes Pfau wrote:
> As I had some free time and nobody else stepped up I implemented it,

I tried it before but I wanted to create whole crypto package at once, 
and I guess it was a huge mistake. I know you have used my code in your 
uuid module, you can use it to add it to std.hash if you want. There are 
all SHA implementations, MD5 and a Tiger (both versions). They all 
support bit hashing and work with CTFE.

I made a quick look at your proposal, but currently don't have time to 
do a deep investigation :). One note though. I don't think it's 
neccessary to maintain two different API sets. Sure, classes need heap 
allocation but usually that's only one allocation, it's more important 
to not allocate during algorithm computations. Fortunately crypto 
algorithms don't do this. So, struct allocation efficency is negligible 
here. I think separate struct based API set is not worth it (or I'm 
missing something not related to allocation cost).