obscache: update the cache key in place
Instead of computing the key in place, we update the existing one using the
data used for the incremental update of the content. This will help reaching
purely incremental cache eventually.
The 'getcachekey' function is dropped as it is no longer used.
all: tutorials/tutorial.rst static/logo-evolve.ico
sphinx-build . ../html/
tutorials/tutorial.rst: tutorials/tutorial.t
python test2rst.py tutorials/
static/logo-evolve.ico: static/logo-evolve.svg
convert -resize 36x36 static/logo-evolve.svg static/logo-evolve.ico