Introducing vibe.d!

[Puming]

Excellent work Sönke! Vibe.d seems very promising :)

I've played with vibe.d with a hello project as described in the
document, and downloaded vibenotes and vibeblog from git and
poked around a little.

vibe.d gives me a very smooth experience, and I'll try learn
about it more :)

two little things to note:

1. In the tutorial it didn't say how to start vibe.d project. I
spent some minutes to find it: by running vibe at the root of a
project. Maybe its clear to state that in the tutorial

2. It seems that diet templates doesn't support soft tab. I
looked into the code, and in indentLevel(line) it only dectects
'\t'. Will vibe.d support soft tab?