Add some automaton flow constraints checks for SMTLIB about dolmen HOT 4 CLOSED

Well I rather meant to check that no assertions were somehow "lost", i.e. that things such as push; assert; check-sat; assert; pop did not occur, because here the second assert is unused and it's likely a mistake, but it would be only a warning and not an error.

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Admittedly, the check-list was mainly for me to remember what I wanted to add, and may have been misleading to others, ^^

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Headers are now checked thanks to cd9127f

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ensure that there are check-sat at each level of push/pop

Is it really mandatory? I can imagine case where you want to add assertions whenever possible and a solver could start solving even before having a check-sat if they want, but without blocking with an explicit check-sat.

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