Add unittest to test collection of C sources and headers

Make getDUBExePath returns a NativePath

review adjustments

fix typo(s)

Merge remote-tracking branch 'upstream/stable' into merge_stable

reduce dependency on the working directory ...

Improves library API usage and bugs with the build generator

fix cyclic dependency of dub.internal.utils

replace std.variant with std.sumtype (#2550) ...

Variant is quite big and runtime heavy, with sumtype we already cover
wrong type cases at compile time.

Fix various DDOC warnings

Revert "Remove Vibe.d HTTP support / library-nonet" ...

This reverts commit db49cbe.

Replace all instances of mkdirRecurse with ensureDir ...

All usages actually want to ensure the directory is present,
and don't care about having a separation between existence check
and creation.

Move foreign code from global scope to dub.internal. ...

Avoids conflicting with the actual dub packages when working with dub as a library. Also, even if just by convention, it ensures that dependent code doesn't rely on this code as a public API.

Move existsDirectory next to existsFile ...

It doesn't make sense to have those in two separate modules.

Unify reading and writing files under a single API ...

This removes the range API and instead uses Appender,
while using a limited and centralized set of functions
to read/write from files.
The end goal is to permit dependency injection,
which is a pre-requisite to extending the test-suite.

Remove Vibe.d HTTP support / library-nonet ...

library-nonet has been broken for years, and is not used.
Most importantly, it has no support for timeout.
Lastly, the likely reason it was originally introduced was to
avoid a hard dependency on cURL, something that has been fixed
in Phobos directly.

vibecompat/core/file: Publicly import path, not URL ...

We don't actually use URL here, nor should we,
we use path, so correct the import.

Path: Remove unused isValidFilename private function

Path: Add missing else clause on version statement ...

This was wrong on many level:
- The missing `else` clause meant that the `enforce` clause was always there on Windows;
- The `enforce("Reason")` should have been `enforce(false, "Reason")`,
  as in its current form it would never fail and not serve its intended purpose;
- It was pushing at runtime something that was easily detected at CT;

Fixes #2452 - Accept non-existing file in `sourceFiles`

fixes #2448 - Accept sourceFiles without module declaration

Use configy library to parse dub.json file ...

This will provide a vastly superior UX to the users:
- They will be warned about typos;
- The type information provided will be more accurate and always include file/line infos
  (e.g. no more 'Invalid SemVer versions');
- We can expose a better recipe struct to library users on the long run,
  by separating the actual data DUB uses from what it reads;
- We can be more descriptive about errors / intent, for example by using `SetInfo`;

Trivial: Convert some spaces to tabs

change TAG_WIDTH const to a variable value ...

use it for making error-only output be more readable

Integrate Configy colored output with dub's

Make unittest independent of byte value escape sequence.

Address review by WebFreak001.

Resolve deprecations.

Keep logging functionality out of the public API as requested in https://github.com/dlang/dub/pull/2124#issuecomment-813016939.

Fix indentation style, now using tabs

Fix PowerShell messed-up colors ...

Now winterm.d (which provides partial ANSI/VT100 emulation for Windows
console) respects bg.init and fg.init (Color.init in logging.d) and,
when encountered, restores the background/foreground color that there
was before instead of just setting it to black