Conv_orable made functional and part of pre_env

But for vm, the kernel should be functional now

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16961 85f007b7-540e-0410-9357-904b9bb8a0f7
CoqIDE: scroll to the right position if there is an interp error

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16962 85f007b7-540e-0410-9357-904b9bb8a0f7
Future: better doc + restore ~pure optimization

This optimization was undone because the kernel type checking was
not a pure functions (it was accessing the conv_oracle state imperatively).
Now that the conv_oracle state is part of env, the optimization can be
restored.  This was the cause of the increase in memory consumption, since
it was forcing to keep a copy of the system state for every proof, even the
ones that are not delayed/delegated to slaves.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16963 85f007b7-540e-0410-9357-904b9bb8a0f7