Documentation converted to reST

I had to drop the Japanese doc, but I'd be happy to restore it in reST format.

doc/Makefile

@@ -0,0 +1,16 @@
+RSTCSS = $(shell python -c 'import docutils.writers.html4css1 as m; print m.Writer.default_stylesheet_path')
+RSTOPTS = --stylesheet-path=style.css,$(RSTCSS) --initial-header-level=2
+
+HTML = $(patsubst %.rst,%.html,$(wildcard *.rst))
+
+.PHONY: clean
+
+all : html
+
+html : $(HTML)
+
+%.html: %.rst style.css
+	rst2html $(RSTOPTS) $< $@
+
+clean:
+	rm -f $(HTML)