Dependency: Expose `visit` to `match` on `SumType` ...

To do so, we need to expose `VersionRange`.
The function is a free function as it otherwise triggers
a deprecation for dual contexts due to the template parameters.

Add some const qualifiers to Repository

Trivial: Remove workaround for DMD v2.070

Trivial: Fix indentation of a log statement

Trivial: Sort inner type in Dependency consistently

Dependency: Ensures call to version_ are on version-containing object ...

The initial port of Dependency to SumType kept full backward compatibility
for ease of use and review, but we can start now to weed out bad usages, if any.

Deprecate Dependency.matchesAny in favor of VersionRange

Trivial: Update comments on PackageManager ...

The previous comments were a bit misleading.

Rename private packagemanager : Repository to Location ...

Avoid ambiguity with dependency : Repository and matches PlacementLocation.

Deprecate duplicated enum LocalPackageType -> PlacementLocation ...

Two enums, both have the same values, in the same order.

settings/selections: Only warn on unknown keys, add changelog ...

This will give users the time to adapt, without erroring right away.

Support escaped forward slashes in YAML parser ...

Integrate fix for issue dlang-community/D-YAML#302 .

Move environment read outside of DependencyResolver ...

Reading environment variables from random places in the code makes
the flow harder to follow, and unittesting harder.
This moves one environment reads to the `dub` module,
which performs many of them already.

Trivial: Change max_iterations type to ulong

Parse settings.json using configy ...

This will provide superior error messages to the user,
and match what we already do for `dub.selections.json`.

It also allows us to remove many fields from the `Dub` class.
Those fields existed so that we would not have to re-compute the data
from the JSON DubConfig was storing. Now that we use a simple struct,
and do the aggregation eagerly, all of that complexity can go.

Incorporate review by Jan Jurzitza <gh@webfreak.org>.

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/Update some tests and make some info messages more similar to original version of Dub

Fix rebase errors

Fix some older DMD frontend versions not compiling logging.d

Fix really stupid error in previous commit

Replace --no-colors & --force-colors with --colors={auto|on|off}

Add --force-colors option to force colors enabled

Add --no-colors option to disable colors in terminal ...

Minor: changed function name in logging module

Revert logInfo to print a single line after a fetch

Minor code style fix

Fix indentation style, now using tabs