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

New logging module - initial functionality ...

The new module replaces dub.internal.vibecompat.core.log by using the
same function names, but implementing colored output and the left
fixed-width tag. Overloaded functions are provided to output colored
text.

Still missing initLogging() and non-TTY stdout/stderr detection

Dependency: Remove dead 'isSCM' code from Version ...

Before `Dependency` was made to use `std.sumtype`,
the code was piggybacking on a field `VersionRange m_range` to store
the git reference whenver the `Dependency` was a `Repository`.
Since this is no longer the case, we can remove this exception from `Version`.

Dependency: Convert to a discrete type ...

A major issue when dealing with the 'Dependency' type is that it evolved from a simple type,
which stored a version range and perhaps one or two boolean,
to one that stores 4 kinds of dependencies: version range (including exact version),
branches, repository + hash, and path.
Instead of using a discrete type (e.g. a tagged union), the type is a mix of style,
and repository and branch are piggybacking on the field used for the version range.

Switching to std.sumtype makes interaction between fields more obvious.
Most importantly, it forces the programmer to answer the hard questions,
such as how do we compare completely different dependency (version vs repository).

Hopefully this will make the code easier to understand, and in the future,
make it easier to add a new kind of dependency.

Add VersionMatchMode support to VersionRange.matches

Suppress `version` for path-based deps in Dependency.toJson() ...

As in dub v1.29 and before.

Dependency: Remove top-level safe, apply to decl ...

A top level safe means that we cannot have templates in this structure
that infer their safety, which can be severely limiting.

Dependency: Change format for path-based dependencies (#2316) ...

* Add missing attributes to NativePath.empty

* Dependency: Change format for path-based dependencies

Deprecate duplicated JSON serialization for Dependency

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`

Trivial: Use Dependency's matchesAny / isExactVersion more consistently

Dependency: Add attributes to optional / default_

Dependency: Remove toHash overload ...

It doesn't take all fields into account and there doesn't seem to be a justification for it.

Trivial: Simplify Version.matches

Merge pull request #2305 from Geod24/move-stuff-in-versionrange ...

Move some version-only constants and helpers in VersionRange

Signed-off-by: Nicholas Wilson <thewilsonator@users.noreply.github.com>
Merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

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`.

Dependency: Make Any/Invalid manifest constants in VersionRange

Dependency: Move matchesAny / isExactVersion to VersionRange ...

Those property make much less sense when we are using path / repository.

Add attributes and scope annotation to Dependency.Version / semver

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

Conflicts:
	source/dub/dependency.d

Also let getBestPackage use VersionMatchMode.strict for managed packages.

Match versions of cached packages exactly. ...

Uses exact version matching instead of SemVer matching for cached packages to enforce exact matches for SCM based dependencies in particular.

Dependency: Isolate SemVer version logic in its own struct ...

Currently, Dependency is a mesh of logic, having evolved from a SemVer + branch only
version specification to semver, branch, path, repository.
In order to bring it under control, and attempt to have a smarter dependency matching,
we must first isolate the different ways we specify dependencies.

Replace deprecated keyword `body` with `do`

Refactor imports.

Support dependencies as git url with exact commit (#1798) ...

* Support dependencies as git url with exact commit

* Compare hashes for SCM

Remove some unused variables ...

There are plenty left, but those ones didn't seem to have any side effect.

[dip1000] Fix compilation and test it on Travis CI

[scope] [Dependency] Don't annotate constructor parameter with scope ...

When the `in` parameter storage class changes its meaning to `scope const` we would get
the following errors:

source/dub/dependency.d(83): Error: scope variable `ver` assigned to `this` with longer lifetime
source/dub/dependency.d(84): Error: scope variable `ver` assigned to `this` with longer lifetime

This commit fixes this.

Add semver compatibility operator "^x.y.z". ...

Matches all versions that are compatible with the public API x.y.z.