giving more examples, some rework
some rework related to composer.
changed "snapshot" to the more former "dev"
changed semver link to the github version of the file.
changed namespace to \PSR\PharApi
changed wording "groupid" to "vendorid"
changed composer.json logic
changed api; added version interface and optional repository interface
closed because there seems to be a big misunderstanding of the groups topic and the groups goals. will not do any additional work on this. sorry.