Generate Hackage-upload compatible cabal package

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Currently generated cabal file does not meet the hackage-uploadable package standard.
In the long run, we should use a more structured way (Cabal AST) for cabal file generation.

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Decided to hand-adjust the current projects (stdcxx, OGDF, hgdal and HROOT-*) for 0.7 because this task is too big a blocker. Aim at 0.8 target though.