fix make mlidoc
Coq_makefile: Allow empty logical names

I'm not sure that coqdep and coqtop understand them correctly anyway ...
Fixup leading ./ path cleaning
Adding printer for named_context_val and Goal.goal in debugger.
A version of convert_concl and convert_hyp in new proof engine.

Not very optimized though (if we apply convert_hyp on any hyp, a new
evar will be generated for every different hyp...).
Removing Convert_concl and Convert_hyp from Logic.
Added support for having one subgoal inheriting the name of its father in Refine.
Propagating name of goal to main subgoal in cut and conversion tactics.
Restoring plugins/xml/README erased by mistake.
No need anymore for referring to xml directory in MLINCLUDES.
Fix segfault in native compiler on int31 division.

Thanks to Yves for reporting it!
Adding an evar version of the make_clenv function.
Using new clausenv in rewrite.