D2 port of xfBuild (alpha version)

[Andrej Mitrovic]

xfBuild is a D1 & D2 build tool, it was written for D1 and Tango by
Tomasz Stachowiak. I've ported it to D2 and Phobos, which will
hopefully enable it to grow thanks to the fairly active D2 community.

Grab it from:
https://github.com/AndrejMitrovic/xfBuild

Currently it compiles simple projects, and was tested on XP SP3 and
Lubuntu. It also appears some multithreaded bugs have disappeared
since I'm now using the new std.parallelism module.

*Note*: This is an alpha-release. I'm pretty sure there are many
lurking bugs ready to be discovered. Don't try to use it on production
code!

Why did I do this? Because I have time to burn. :-) (also I've heard
Tomasz used his tool on very large codebases, so it's a project worth
porting)