Rework dia -> pdf pipeline for inkscape 1.0

• Use dia directly to convert from .dia to .svg (inkscape would use dia via a plugin anyway)
• Add proper runes to detect inkscape >= 1 and use the export options for that.

Test Plan

make -C docs/images

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Migrated from D3489 (view on Phabricator)

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Patch application report for D3489 (id=12336)

Rebasing onto 0547a516...

Current branch diff-target is up to date.

Changes applied before test

commit bf4353663b2caa7e3492905f14fbfbc93758b560
Author: Nicolas Dandrimont <nicolas@dandrimont.eu>
Date:   Thu Jul 9 19:35:21 2020 +0200

    Rework dia -> pdf pipeline for inkscape 1.0
    
     - Use dia directly to convert from .dia to .svg (inkscape would use dia via a
     plugin anyway)
     - Add proper runes to detect inkscape >= 1 and use the export options for that.

See https://jenkins.softwareheritage.org/job/DMOD/job/tests-on-diff/122/ for more details.

Merge request was merged

closed