Fix null pointer dereference in Project.this() when no package was found. Fixes #286.

Avoid exponential run time in the dependency resolution algorithm if possible. ...

When going through all combinations of package versions, all sub trees of the search space are now skipped for a conflicting node, as those are guaranteed to conflict anyway.

Handle packages with invalid package descriptions gracefully and improve diagnostic output.

Fix compilation on DMD 2.064.

Fix path based dependencies to be ignored for version selections.

Fix unit tests of DependencyResolver.

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.

Fix resolution of optional and path based dependencies.

Disable log output during "dub describe" to ensure only JSON gets written. See #221. ...

Note that JSON will only get written when no errors occur. Otherwise the output will be the usual error messages.

Add command line interface for managing package overrides.

Correct copyright notices.

Mention using DUB as a library.

Refactor runDubCommandLine to use less indentation/nesting.

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

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

Fix getting the versions of each package during dependency graph resolution.

Generate less noise for up to date dependencies.

Only validate (and output warnings) the root package once.

Reinitialize the project after upgrading dependencies.

Output -l flags on the compiler command line after all source files. Fixes #281.

Fix handling of overriding selections and let printUpgradesOnly fail gracefully.

Improve the warning message for branch based dependencies.

Fix dependency resolution for outdated invalid dependencies. ...

Now the invalid dependency is simply ignored as long as it isn't actually chosen.

Add a warning message for packages that use branch based dependencies.

Move DependencyResolver to its own module and reorder Version<->Dependency.

Rename Project.mainPackage to rootPackage. ...

Root package better describes the package's role of the root of the dependency hierarchy.

Fix 64-bit compilation.

Compile fix for DMD 2.064.

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

Rename fields in Project and load the root package only once.

Merge pull request #283 from John-Colvin/patch-2 ...

Fix imports for DMD master.