evolve: specify the 'minimalhgversion'
3.7 added a new nice and shinny variable to help user know when they use the
wrong version of Mercurial with an extension. We now use it.
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