obshistory: add a debugobshistory command to show obs history of a revs
Add the debugobshistory command that accept a revision range and display
the obsolescence containing each revision in the range.
For the moment, it only displays the predecessors.
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