Upstream merge of master

added 3 commits

• 97de2ae4 - Stop Linux servers from hanging every 34 hours
• 67e721e9 - Merge branch 'need-more-time' into 'master'
• 3fe3d112 - Merge remote-tracking branch 'upstream/master' into upstream-merge

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added 3 commits

• d865b566 - CircleCI: test build SRB2 without network support
• 0051eb70 - Merge branch 'circleci' into 'master'
• 94bd0e39 - Merge remote-tracking branch 'upstream/master' into upstream-merge

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srb2icon.png needs to be replaced before this can be merged but I don't have the assets required to replace it handy

added 6 commits

• 94bd0e39...77997329 - 2 commits from branch master
• f8237686 - Fix building without BLUA support
• ae368a3e - Merge remote-tracking branch 'upstream/master' into upstream-merge
• 24ae6107 - Exported SDL_icon.xpm as srb2icon.png
• c56cae4d - Merge remote-tracking branch 'origin/master' into upstream-merge

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added 1 commit

• d4f05e5b - fixup merged mess for NO-LUA mess

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merged

mentioned in commit 2a672dbd