Remove version branches for no-longer-supported compilers

Turn some enums into [static] immutable

Remove unused branch

Revert "support dependencies as git url with exact commit"

Merge pull request #1765 from belka-ew/pr_vesion_commit2 ...

support dependencies as git url with exact commit
merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

Command dub lint added

Support dependencies as git url with exact commit

Merge pull request #1755 from kinke/ldc ...

Improve user experience with ldc2, incl. cross-compilation
merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

Improve cross-compilation support (replace `version` checks by BuildPlatform runtime checks) ...

Also fixes #1249. For LDC as implicit cross compiler, the file
extensions for libraries and object files etc. don't depend on the
compiler, but solely on the target. Targets selected with `--arch` are
correctly probed by dub, so that the parsed `BuildPlatform` represents
the target platform.

Support fetch sub-package

Project settings file

`alias Nullable.get this` will soon be deprecated. Use `.get`.

Support of init-exec sub package

Custom init type (#1658)

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

also remove dead code-mirror2.dlang.io fallback

fix Issue #1522 - avoid insecure fallbacks ...

- opens dub for possible MITM attacks

improve package supplier fallback logic ...

- scope (failure) did swallow fatal errors
- improve logging of failures and successes
- rethrow failure of default registry instead of from the last one
- remove failing package suppliers, so we don't keep beating dead horses

Note that some retry logic is already done interally by package suppliers,
so a failing one is unlikely to recover on the next usage.

Merge pull request #1616 from andre2007/fix_issue_1401 ...

Filesystem package supplier updated
merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

Filesystem package supplier updated

Merge pull request #1589 from MartinNowak/filter_version_identifiers ...

Add experimental feature to improve build cache efficiency

call setDifference with SortedRange ...

in preperation for

https://issues.dlang.org/show_bug.cgi?id=10706
https://github.com/dlang/phobos/pull/6795

the passed string[] are sorted so assumeSorted is ok.

infer unspecified version filters ...

- otherwise of little use as all dependencies need to have specified
  version filters before this can be used
- also version identifiers are fairly easy to grep for
- cache inferred version filters
- still allows explicit specification for packages that use version
  identifiers in mixins

Merge pull request #1526 from andre2007/fix_issue_1524 ...

Late dependencies resolver
merged-on-behalf-of: Jan Jurzitza <gh@webfreak.org>

Merge pull request #1481 from SimonN/issue1478-quote-xcopy ...

Fix #1478 - Quote paths passed to xcopy

Use default architecture for ddox

Fix #1478 - Quote paths passed to xcopy ...

On Windows, `cd` accepts unquoted paths, but for any calls to `xcopy`,
paths arguments must be double-quoted. This patch surrounds all paths
with double-quotes before passing them to `xcopy`.

This fixes #1478: On Wine (and presumably Windows XP), migrating the dub
package directory from dub 1.7 to dub 1.8/1.9 via `xcopy` failed an
enforce in dub (because `xcopy` quit with nonzero exit code) and thus
prevented even the most simple dub projects from being built.

D WYSIWYG strings (backtick-surrounded strings) allow all characters
unescaped, including double quotes and backslashes.

Maven upgrade dependency tree

Clean sub-packages when main package target type is "none"

Support more vars in build settings ...

fixes dlang/dub#1447