ostree v2020.7

["Colin Walters" <walters verbum org>]

https://github.com/ostreedev/ostree/releases/tag/v2020.7

Static deltas can now be signed to more easily
support offline verification.

There's now support for multiple initramfs images;
the idea here is that one can have a "main" initramfs
image and a secondary one which represents local
configuration.

The documentation is now moved to https://ostreedev.github.io/ostree/#

A lot of preparatory cleanups to the pull code landed
for upcoming work on indexing deltas outside of the summary.

On the bugfix side, the biggest one is a fix for
an assertion failure when upgrading from systems
before ostree supported devicetree.

Also notable is that ostree no longer hardlinks zero
sized files to avoid hitting filesystem maximum
link counts.

Thanks to all contributors!

```
Alexander Larsson (17):
      list-deltas: Don't break on non-subdir entries
      Fix leak when signing
      pull: Break out _ostree_repo_save_cache_summary_file() helper
      pull: Actually mmap summary files
      Add and use ot_checksum_bytes helper
      deltas: Break out _ostree_repo_static_delta_superblock_digest() helper
      Break out the signature verification code into a helper function
      fetch_summary_with_options: drop unnecessary "goto out" use
      Add g_autoptr helper for pushing a thread default main context
      repo_remote_fetch_summary: Use GMainContextPopDefault
      Inline repo_remote_fetch_summary
      Minor cleanup of _ostree_repo_remote_new_fetcher()
      ostree-repo-pull.c: Extract mirrorlist generation to helper
      Update the symbols files to match that we're now on 2020.6
      ostree_repo_find_remotes_async: Fix leak of summary
      fetch_summary_with_options: Fix n-network-retries option parsing
      signatures: Fix leak in _sign_detached_metadata_append()

Colin Walters (10):
      Post-release version bump
      ci: Drop var mount test
      deploy: Add some error prefixing around xattr setting
      commit: Tighten scope of two variables
      checkout: Ensure copies of unreadable usermode checkouts are readable
      deploy: Remove deployment bootcsum assertion
      delta: Some minor code style fixups
      checkout: Don't hardlink zero sized files
      libglnx: Bump to master
      Release 2020.7

Frédéric Danis (12):
      lib/deltas: Add inline signature for static-delta superblock
      bin/static-delta: Add support to sign superblock
      lib/deltas: Add signature check API for static-delta superblock
      bin/static-delta: Add command to verify delta signature
      lib/deltas: Support signed delta in execute_offline
      lib/deltas: Support signed delta in dump
      tests/delta: new tests for signed deltas
      tests/libtest.sh: Add skip_without_sign_ed25519() function
      tests/delta: new tests for 'ed25519' signed deltas
      lib/deltas: Check signed delta in execute_offline
      bin/static-delta: Add signature parameters to apply-offline
      tests/delta: Add new tests for applying signed deltas

Jonathan Lebon (8):
      Makefile-libostree.am: Uncomment BUILDOPT_IS_DEVEL_BUILD conditional
      lib: Minor versioning related fixes
      lib/bootconfig: Add support for multiple initrd keys
      lib/deploy: Add deploy/stage APIs with options
      lib/deploy: Add support for overlay initrds
      Add Packit integration
      lib/deploy: Don't leak fd when checksumming dtbs
      ci: Make Packit ignore downstream patches

Phaedrus Leeds (1):
      Avoid shadowing local variables

Philip Withnall (3):
      lib/repo: Add mode and tombstone config options to the summary file
      lib/pull: Read mode and tombstone options from summary file if possible
      ostree/dump: Fix a memory leak

Timothée Ravier (7):
      docs: Add Jekyll and theme config
      docs: Update Index page
      docs: Update Contributing and tutorial pages
      docs: Move and update pages from the manual
      docs: Move historical README to the docs
      README: Update and mention new docs
      docs: Fix URL in Jekyll _config.yml
```

Git-EVTag-v0-SHA512: 
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