Make Phobos module examples runnable

[wilzbach]

With the new RUNNABLE_EXAMPLE Ddoc macro, in theory we just need to slap it around documented examples that can be run online.
Of course, the requires a valid main method, imports etc. and examples without output are quite boring to the reader.

This is a test to see whether more work is required or it "just works".

edit: this now just converts documented examples into real unittestss, testing the new RUNNABLE_EXAMPLE Ddoc macro will happen in another PR.

[dlang-bot]

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[wilzbach]

@meh DPaste seems really restrictive and it's time it gets overhauled or replaced:

• std.concurrency -> segfaults (works fine with the DTour)
• std.csv -> permission errors (works fine with the DTour)
• std.zip -> permission errors (works fine with the DTour)

TODO

I removed all tricky bits from this PR.
Stage 2 should include at least this:

• std.base64
• std.demangle
• std.getopt
• std.regex (third example has assertion failures)
• std.uni
• std.zip
• std.zlib

[wilzbach]

Examples of how this will look are on DAutoTest, e.g. http://dtest.dlang.io/artifact/website-d47df2c302b4a710bf285a86fc8e3417827dd7b8-0867404c3823f79c76cd98ee9f462b20/web/phobos-prerelease/std_csv.html

[CyberShadow]

Seems like currently it breaks the DDox module examples.

[PetarKirov]

I would prefer making those examples into (possibly module-level) documented unittests, where possible.

[wilzbach]

I would prefer making those examples into (possibly module-level) documented unittests, where possible.

Same here - as you might remember I have pushed for this in the past already:

#4042, #4044, #4045, #4066, ...

In these cases, the examples use stdout and create files, so it's a bit tricky to make to convert them to unittests. However, I think I managed to do this for a few modules and left the other ones for the future when I (or someone else) has time to look at the Ddox errors.

[wilzbach]

I am not a huge fan of this workaround, but this allows us to use writeln in the unittest below and thus convert the documented example to a unittest without loosing out on features. Better ideas are, of course, welcome.

[wilzbach]

I added these four lines as tuple is nearly equally important as its big brother Tuple