Add VERSION file

[andralex]

This file dictates the current version. All projects needing the version can fetch it from here.

[yebblies]

@andralex Not to doubt you... but why?

[andralex]

@yebblies why what?

[yebblies]

I'm curious what this file is meant to be used for.

[andralex]

Oh I see. We have several points in the build process where the version number must appear in clear (including e.g. the download page and the documentation), not to mention the compiler proper. So far we did it all by hand, and of course things are forgotten (for example the download page accessed 2.060 for a couple of days after the release).

Having the version in one place will allow us a unique point of maintenance.

[ghost]

Just a FYI for anyone unaware you can use __VERSION__ programmatically in D, e.g.:

static assert (__VERSION__ >= 2060, "Requires compiler 2.060 or newer");

This also works for GDC, and probably LDC too since it shares the same front-end. Also a good trick for build-tools:

rdmd --eval=write(__VERSION__)

But maybe the version file is still necessary for other tools.

[9rnsr]

I opened #1469 to use VERSION file.