engine.Env: comments and tests for Get()

Signed-off-by: Vincent Batts <vbatts@redhat.com>
Fixed typo
Update remote_api_client_libraries.md

Adding docker rust client lib.

Signed-off-by: Abhinav Ajgonkar <abhinav316@gmail.com>
Fixed a typo in docs (outpu -> output).

Signed-off-by: Lakshan Perera <lakshan@laktek.com>
builder/parser/dumper: Handle newlines appropriately.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder/parser: fix handling of empty strings as the only argument.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: Fix a small bug that could improperly cache.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: Fix entrypoint and cmd semantics in evaluator. Test c/o @cnf

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
evaluator: ensure entrypoint stays blank if set blank while CMD is set.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Do not populate path to prevent runconfig merge conflict; remove
autoConfig seeding of entrypoint.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
move entrypoint integration-cli test for blank entrypoint to separate function

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: Fix an error check being done at the wrong spot in run
dispatcher

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Add notes about single-quotes

Signed-off-by: Doug Davis <dug@us.ibm.com>
Merge pull request #7984 from vbatts/vbatts-engine_env_comments

engine.Env: comments and tests for Get()
Merge pull request #7806 from erikh/fix_cmd_handling_in_parser

Fix cmd and entrypoint handling in parser
Merge pull request #7202 from timbot/add-registry-mirror-flag

Add daemon flag to specify public registry mirrors
Removing an image that fails, also removes the image name/tag.

Fixes #7845 and #7801, and a real pain point I had :)

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Match docs to actual port range used in code.
Addresses #7985

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Validate tag names similar to repository name validation; add tests
Addresses #7943

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Merge pull request #7959 from crosbymichael/update-libcontainer-sep6

Update libcontainer to 84ad9386a0240acb7475429a835