Use "dub.json" instead of "package.json" in documentation

Do not store sub packages of "add-local" packages and fix removeLocalPackage.

Various improvements. Fixes #268. ...

- Treat all package paths as ending with a slash to fix path comparison issues
 - Avoid re-reading all packages twice when building, see also #325.
 - Fix bogus "License in subpackage different" warning

Fix version overrides with a recursively matching target version.

Resolve sub packages of the root package directly instead of using the package manager. Fixes #287.

Let Dependency.toString() also contain the optional/path properties. ...

versionString is changed into a public property to support the use cases where only the version range is expected.

Add command line interface for managing package overrides.

Implement user/system wide overriding of certain package version ranges. ...

What is still missing is a command line interface for conveniently setting the overrides.

correct imports

Merge branch 'dustmite'

Improve error message when removing a package fails.

Removing not needed check for git version when installing a package from the registry.

Not catching Throwable when metadata is fetched. ...

Documentation updated.

Fix automatic removing of packages. Path's created for directories were missing a ending slash '/'.

Add --force-remove switch and reimplement PackageManager.remove. ...

remove() now first checks for untracked files and leaves the package untouched if it finds some and no force_remove is supplied. This means that after the user gets an error concerning untracked files, it's possible to rerun dub with --force-remove to remove the package cleanly.

Improve error messages for errors during package removal.

Print a more descriptive error message when PackageManager.getTemporaryPackage fails.

Avoid scanning for local packages for "dub dustmite --test-package".

Add Dub.overrideSearchPath to define a single and only path that is searched for packages.

Fix triggering an enforcement for Version.INVALID.

Determine the version of the package in the root dir properly instead of assuming ~master.

Make the warning message for non-existing locals more helpful.

Fix null pointer access for non-existent locally registered packages and output a warning.

The externally defined sub-packages don't have the name declared in the base package. This eliminates the double definition of a sub-packages name.

Fix check for looking only at base packages in PackageManager.getPackage. Fixes #214.

Properly saving the journal's filename of the package description.

Keeping track of the saved json file in the journal and some smaller changes.

Make "dub.json" the primary choice for a package description and handle "package.json" as a fallback.

When a package having externally defined subpackages is installed, they work. Currently not tested with the registry.

Automatic discovery of sub-packages added to package manager.