- packages are now wrapped into a `"packages"` top level key instead of the whole file being the package array
- packages now contain an `"installed-path"` key which lists where they were installed
- there is a top level `"dev"` key which stores whether dev requirements were installed or not
- `PreFileDownloadEvent` now receives an `HttpDownloader` instance instead of `RemoteFilesystem`, and that instance can not be overriden by listeners anymore
- `PreFileDownloadEvent` now receives an `HttpDownloader` instance instead of `RemoteFilesystem`, and that instance can not be overridden by listeners anymore
- `IOInterface` now extends PSR-3's `LoggerInterface`, and has new `writeRaw` + `writeErrorRaw` methods
- `RepositoryInterface` changes:
- A new `loadPackages(array $packageNameMap, array $acceptableStabilities, array $stabilityFlags)` function was added for use during pool building