doc: api: document Query.
removed PycompDict
groups: also display available environment groups. (RhBug:1029948)
rename: Base.group_lists -> Base._group_lists.

To make it look clearly non-API.
doc: api: document the dnf.subject.Subject API.
fix: installs globbing for a file without a slash at the start. (RhBug:1030998)
doc: api: document dnf.transaction.Transaction.
Handle remote URLs. (RhBug:1030297)

Set the tempfile extension to ".rpm", add_cmdline_package() needs that.
Reference it from the base to prevent GC. Close/unlink it on shutdown.
remove: dnf.yum.misc.re_remote_url()