Unify package path in a single PackageManager function ...

The idea is that PackageManager should be responsible for packages on the disk,
and the first step to do that is remove the leakage of path happening in the Dub class.

Trivial: Deprecate Dub.remove(Package, bool) ...

The corresponding PackageManager function is long deprecated,
but the Dub wrapper was not deprecated.

SpecialDirs: Re-order by priority, document

Refactor SpecialDirs initialization in its own function ...

Take the IO-performing code in a single function so later on
we can better isolate it for library users.

Trivial: Deduplicate GeneratorSettings initialization

Trivial: Remove a leftover debug statement

Deprecate `PackageManager.loadSCMPackage` & other `Dependency`-related refactoring (#2312) ...

* Trivial: Take a nested function out of a foreach loop

* Deprecate PackageManager.loadSCMPackage's Dependency overload, use Repository

We're moving away from using `Dependency.m_range` to store the git ref,
and the `Repository` type has already been updated to include the information,
but some places still read it from `m_range`, including this one.

* Trivial: Forward Dependency's string ctor to VersionRange ctor

* Trivial: Simplify comparison with `VersionRange.Invalid` within `VersionRange`

SelectedVersions: Add Repository to overload set (#2314) ...

Before it was an independent function because it had a different set of parameters,
but now that it has been unified, we can put it in the overload set.
No deprecation since the previous change that deprecated selectVersionWithRepository
hasn't been released yet.

Various code simplification around `dub.selections.json` (#2311) ...

* Deprecate unused Json constructor

* Trivial: Fix import order in dub.project

* Simplify DependencyResolver filtering

DependencyResolver is only instantiated from one place, and never re-used.
It makes more sense to set those variables in the constructor,
and avoid repeatedly calling a single function.

* Move file format to dub.selections.json to its own struct

Our goal is to replace the handcrafted JSON code with configy.

Trivial: Remove an always-true if (#2313) ...

Since we are using a path-based dependency, dep.matches will always return true.

Dependency: Move `spec` / git ref inside of `Repository` ...

The `Dependency` struct is logically acting as an `enum`,
with 3 discrete possibilities. However, some of the logic is
piggybacking on the (original) version logic.
`Repository` is one of them, and by separating things,
we can make stronger assumptions in `Version` and `Dependency`.

getDefaultConfiguration(): Accept a const BuildPlatform argument ...

Like `Package.getDefaultConfiguration()` already does. Fixes a minor
annoyance for reggae.

Use Dependency.any whenever possible

Merge remote-tracking branch 'origin/stable' into merge_stable ...

Conflicts:
	source/dub/dependency.d

Also use strict version matching for cached packages when determining the need to fetch a dependency. ...

Fixes #2262.

Fix dub_test_root imports for non-all-at-once compilations (#2288) ...

Which requires a regular `dub_test_root.d` filename *and* adding
the containing directory to the importPaths.

Make `dub describe -c unittest` auto-generate dub_test_root.d if required
Except with `--annotate` for a dry run.

Add a command line option for upgrading all sub packages. ...

Allows to upgrade all path based sub packages of a package, in addition to the package itself, in one go. See also #1245 and #2284.

Handle unittest config special case in Dub.generateProject()

Refactor Dub.testProject() to Project.addTestRunnerConfiguration() ...

With some slight functional changes in Dub.testProject() - not
resetting m_project and creating the generator with the final
project.
And some minor log output changes.

Fix #1856 - enable building the special test runner config

Posix: use /etc/dub/settings.json if in /usr ...

Fix #1472

/etc/dub/settings.json overrides /usr/etc/dub/settings.json (as
suggested by the `man hier` manpage)

Fix issue 2051 failing CI

Remove line 'Excluding package.d blah...' from default dub build

Fix #2141 - When used as a library, the default compiler is different from the expected. (#2158)

Add environment variables to BuildSettings (#2121)

only show package.d warning once

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

fixed a bug with DFLAGS environment variable and cached generated unittest

Add lowmem for settings

Add the main source file directory to import paths ...

else dub doesn't find it because the single file package do not have the default package directory structure