STM: save a full state for queries.
STM: save a full state for queries.

In PIDE based UIs queries can be delegated too, hence to speed up
things I was saving a shallow state.  Unfortunately a shallow state
breaks section/modules commands, and a query can be the last entry
of a section/module.  (A shallow state does essentially drop the libstack).

The easy solution is to save a complete state.
A better one would be to refine the static analysis of the document and
decide which kind of saved state one needs.

TheTypoMaster/coq,JasonGross/coq,ppedrot/coq,coq/coq,ppedrot/coq,Lionel-Rieg/coq,herbelin/github-coq,coq/coq,JasonGross/coq,jpdeplaix/coq,TheTypoMaster/coq,letouzey/coq-wip,silene/coq,Matafou/coq,Ptival/coq,SkySkimmer/coq,ejgallego/coq,gares/coq,gares/coq,gares/coq,amintimany/coq,ejgallego/coq,SkySkimmer/coq,maximedenes/coq,jpdeplaix/coq,silene/coq,TheTypoMaster/coq,letouzey/coq-wip,coq/coq,amintimany/coq,barras/coq,letouzey/coq-wip,SkySkimmer/coq,mattam82/coq,william-lawvere/coq,Ptival/coq,Zimmi48/coq,letouzey/coq-wip,JasonGross/coq,maximedenes/coq,ejgallego/coq,maximedenes/coq,Zimmi48/coq,Lionel-Rieg/coq,Zimmi48/coq,gares/coq,maximedenes/coq,barras/coq,william-lawvere/coq,Zimmi48/coq,letouzey/coq-wip,Ptival/coq,Lionel-Rieg/coq,ppedrot/coq,gares/coq,herbelin/github-coq,maximedenes/coq,coq/coq,william-lawvere/coq,jpdeplaix/coq,mattam82/coq,barras/coq,JasonGross/coq,ppedrot/coq,silene/coq,amintimany/coq,ppedrot/coq,Matafou/coq,ejgallego/coq,mattam82/coq,herbelin/github-coq,Matafou/coq,SkySkimmer/coq