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

Add clean-caches command for purging the metadata cache.

Remove PackageManager argument from createProjectGenerator(). ...

The argument is also removed from all Generator sub classes.

add clean-caches command ...

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

Improve error output in case of locally installed packages with errors in the package description. See #421.

Merge branch '0.9.22' ...

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

added unittests for module name parsing

Merge https://github.com/D-Programming-Language/dub

Improve error messages for failures to parse dependency package descriptions. ...

See #398.

Fix repeated download of packages when a non-existent external sub package is referenced. ...

See #398.

Fix access violation when looking for sub packages of non-installed packages. Fixes #398.

Use "_" instead of "$" to avoid potential shell confusion. See #411.

Replace "+" by "$" when storing packages to avoid confusing Optlink. See #411.

Untangle Package and PackageInfo. See #403.

Updated 3 for SDL support

prevent code from searching file system for the package file multiple times

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.

Add upgrade() call when building DDOX to get the required dependencies. Fixes #366.

Don't print possible upgrades of the root package.

Don't try to reinstall (remove) unmanaged branch based dependencies.

Cache the results for upgrade suggestions. ...

The same results are not reused for one day instead of querying the registry every time. Note that this already used to be the case some time ago.

Improve some package upgrade related messages.

Fix UpgradeOptions.printUpgradesOnly. Fixes #323. ...

This commit disables fetching upgrade candidates and prints a message for each upgradeable dependency instead.

Only upgrade branch dependencies when an explicit upgrade is requested.

Force upgrade of branch based dependencies. Fixes #360.

Output a reason when implicitly fetching packages.

Avoid assertion when building path based sub packages (or packages with path based dependencies).

Avoid downloading base package for non-existent sub package references, if possible. ...

When it can be proven that a certain sub package doesn't exist (this is the case when the base package descriptions doesn't contain any path based dependencies), the dependency will be skipped as invalid instead of downloading the whole package to search for the sub package there.

Avoid downloading base packages if possible. Fixes #345. ...

Before manually extracting a sub package from a base package, the package description of the base package is first searched for the sub package. This avoids the otherwise necessary download of the base package whenever the sub package is a non-path-based one. This also opens the way for the dub registry to always collect all sub packages into the reported package description, so that it will never be necessary to actually download a package for getting a sub package.

Fix detection of root package references during dependency resolution. See #334. ...

- References to and from sub packages of the root package are now also recognized as coming from the root package
 - Any dependency reference within a certain package "family"* (including path based ones) is now mapped to the same base package (circumventing the lookup of all possible matches)

* "family" == base package and all of its sub packages

Avoid redundant loading of packages and remove PackageManager.getTemporaryPackage.