correct imports

Integrate the "dub select" functionality in "dub upgrade".

Make some cosmetic changes to dub version selections. ...

- Adjust code style
 - Let "dub select" output a simple package->version map instead of package->{version, dependencies}
 - Rename dub.select.json to dub.selections.json.

Merge branch 'dustmite'

Improve error message when removing a package fails.

Build fix.

Fixing 'dub fetch xyz --version=a.b.c', the latest version was fetched instead of the specified. ...

The problem was that Dependency("1.0.0") != Dependency("==1.0.0") or Dependency(Version("1.0.0")). Similar to the branches, not specifying a comparison operator assumes identical version required.

Preparing dub select command. dub select will select the currently used versions and write them to a file, so that dub can later use this information to rebuild this exact state. This will also be used to override dependencies with either branch versions or not matching versions (to resolve conflicts). (All of this if to be implemented). ...

Other changes:
- Added Version.UNKNOWN, which could be later used for undetermined package versions instead of ~master.
- Added Dependency to/fromJson.
- Added Dependency alias "*" for ">=0.0.0".

Fixing serializeToJson for structs/classes with to/fromJson to/fromString.

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

Not catching Throwable when metadata is fetched. ...

Documentation updated.

Removing superfluous try-catch around dub.remove.

Cleaning up exception handling for dub remove and not catching Throwable somewhere else than commandline.d.

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

Fixing Path.relativeTo for directories, a Path whith endsWithSlash==true had this property stripped, when made relative to another Path.

Fix "dub --rdmd" build everything at once. See #255. ...

Since RDMD already builds everything at once, this would be useless
work and many dependencies don't have the required
mainSourceFile, so that it would make the compilation fail.

Properly handle mainSourceFile for --rdmd. Fixes #263.

Silence debugging log message

Fix linking for DMD 2.065 in Posix (breaks 2.064) when build using DUB

Also warn about using certain "buildOptions" in addition to "dflags".

Fix handling of the --local switch. Fixes #259. ...

--local was erroneously doing the same as --system.

Fix RPM build script to properly handle release versions.

Tag version 0.9.21.

Fix version inference for the RPM build script. ...

The leading "v" of the tag needs to be dropped.

Update change log.

Merge branch '0.9.21'

Following rubygems version specification for approximate version more closely.

Use the cURL-less configuration for unit testing to avoid linker errors.

Use up to date DUB release.

Add build status badge.