simulation: improve merging of transiant-SCCs

* spot/twaalgos/simulation.cc: Code this.
* tests/core/det.test, tests/core/dra2dba.test,
tests/core/satmin.test, tests/core/sim3.test,
tests/python/decompose.ipynb, tests/python/dualize.py: Adjust test
cases.
* NEWS: Mention the optimization.
13 jobs for next in 154 minutes and 55 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
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alpine-gcc

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arch-clang

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arch-gcc-glibcxxdebug

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debian-gcc-snapshot

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debian-stable-gcc

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debian-unstable-gcc-coverage

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debpkg-stable

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mingw-shared

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mingw-static

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rpm-pkg

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  Publish
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dput
publish-rpm

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dput
publish-unstable

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