Merge pull request #1198 from grogancolin/grogancolin/#1167 ...

Retry downloading a package
merged-on-behalf-of: Sönke Ludwig <s-ludwig@users.noreply.github.com>

Remove unused import.

add code-mirror.dlang.io as fallback registry ...

- to handle any code.dlang.org failures

Always throw for 404 errors.

Try 3 times to download a package/metadata ...

Packagesupplier.d now tries 3 times to download a package and metadata.
This should aid travis to not be as flaky as it is currently.

Implements enhancement request #1167

handle expected 404 errors when fetching metadata ...

- and throw any other errors
- also see https://github.com/dlang/phobos/pull/5551 for HTTPStatusException

fix #1104 - log warnings about failing requests by default ...

- making errors like 'unknown package' or 'no package found' actually understandable

Reduce log noise.

Remove deprecated functionality to prepare for 1.0.0.

Mention version of removal for all deprecated public symbols.

Review and document dub.packagesupplier.

fix Issue #528 - fetch doesn't work for recently updated package ...

Revert "store metadata cache on disk"

This reverts commit 161aad0.

We only ask the package suppliers for metadata when upgrading or
searching a specific package version. In particular building an already
fetched package does not ask the package suppliers (only the package
manager responsible for locally installed packages).

In all cases where we get data from a package supplier we want to get
the latest available information. Therefor it doesn't make sense to
cache any metadata from the package suppliers on disk.

Not sure whether we still need the in memory metadata cache (e.g. for
multiple queries during dependency resolution).

fix #674 - cache needs to be locked for concurrent dub runs ...

- implement lockFile/tryLockFile using mkdir
- use lockFile to synchronize package download

implement search command ...

- queries all package suppliers and outputs any found package

Gracefully handle failure to load package cache files.

Merge pull request #433 from MartinNowak/cleanCaches ...

Add clean-caches command for purging the metadata cache.

Improve JSON parser error format. Fixes #317. ...

Errors are now displayed as "file(line): Error: message".

add clean-caches command ...

- purges all dub metadata caches
- currently this is only the cache of the registry package supplier

Merge branch '0.9.22' ...

Conflicts:
	source/dub/dub.d
	source/dub/generators/build.d
	source/dub/generators/generator.d
	source/dub/package_.d

Avoid double escaping of "+" in download URLs. Fixes #411.

store metadata cache on disk ...

- Writing is a little slow due to Json escaping
  so also use a dirty flag to track when a writeback
  is needed.

- The metadata contains readme files for every project,
  strip that data for now because of the point above.

Removed trailing whitespace

Use "dub.json" instead of "package.json" when reading from zip archives

Enable line number display for JSON errors and improve error messages. See #317 and #325.

Expire cache entries in RegistryPackageSupplier after one day.

Use URL and Path types of vibe.d if available for better interop.

Implement a new dependency resolution algorithm with support for selections. ...

The new algorithm is completely rewritten to be able to find any valid combination of dependencies/versions. The old one could error out in cases where a valid dependency tree could have been built. Now the current selections are also taken into account when invoking without UpdateOptions.upgrade.

Some side changes:
 - Comparing branch versions is allowed now to enable sorting the full set of versions of a package
 - DependencyGraph and RequestedDependency have been removed

correct imports

Use "%2B" to replace "+" in URLs when downloading packages. ...

This is not needed for code.dlang.org, but it's the correct approach in general.

Avoid casting RegistryPackageSupplier[] to PackageSupplier[]. Fixes #186.