Rewrote the entire build process.

Fixes #8.
Fixes #63.
Fixes #64.
Fixes #69.

Oof. Total rewrite of the build process. Introduced a dependency
on Python (2.7+ or 3+ should work).
(Using a JS-based automater like gruntjs - or indeed another high-level
build system - seems overkill compared to using a regular Makefile, with
Python scripts for the complex parts.)

With this patch, JS and CSS resources are aggregated and minified by default.

./configure is now a Python script, taking advantage of advanced argument parsing.
Calling ./configure from another directory will create a Makefile there, which
allows building out of source.
make install will copy all resources to the specified target, optionally
placing everything but index.html into a separate destinationg for CDN use.

(An out-of-source build does not have all resources; some are installed directly
from the source directory itself without changes.)
Several fixes to the previous patch that actually
allow building out-of-source.
Set SRC_PATH to .; make `all` the top make target.
Fix the CSS/image relative path issue.
Disable compression when YUI is missing.
Updated the README for the new build process.
README.md formatting.
Use the more up-to-date Releases page of YUI.
Require a valid file for the logo.
Move Makefile to Makefile.in, add a distclean.

The clean command should now remove all generated files and dirs
from the build directory; the distclean will also purge Makefile
and .config.status.

For simplification, and to avoid the problem of running make before
configure, Makefile is now Makefile.in, and will only be copied by configure.

.gitignore got restructured a bit.
Make sure the default file is sourced.
Copy the global CSS files to the global/ subdirectory.
Remove --dirty: basically useless
Fix #51: Add a config.custom.js file.

This file is created but not overwritten by the installer.
Any settings changes that are not supported by the configure script
should be made there.
Actually made debug mode work.

Also added a make target that automatically fetches submodules.
This will not work in a file that isn't a git checkout, which is
something to fix later on.