Make help clearer around how to use UpgradeShell.

Closes #3504
Update version number to 2.5.1
Harden the `bin/cake` script to avoid breakage when local shell environment has a `CDPATH` set.
Add 'feedback' to uninflected single and plurals
Merge pull request #3530 from beporter/feature/bin-cake-cdpath-fix

Harden the `cake` script to avoid `CDPATH` breakage.
Merge pull request #3528 from Marlinc/patch-1

Add 'feedback' to uninflected single and plurals
Fix incorrect status line parsing in HttpSocketResponse.

Allow for multi-word status reasons.

Closes #3545
Fixed secure form hash for special url.

No htmlspecialchars encode and without fragment identifer.
Removed unnecessary conditional branch, fixed test and comment.
Add additional test case for named parameters.

Refs #3525
Merge branch 'secure-form-url-special'

Merge pull request #3525 into master. This fixes additional issues with
form tampering prevention by accomodating more URL types.
Optimize renew().

Don't call session_id() twice when we can use a local variable to store
the current session id.

Fixes #3531
Don't disable the entire select when disabled is array(1)

When the disabled attribute is just array(1), then the attribute should
be filtered out of select element attributes. This is kind of a hacky
workaround but changing the underlying attribute handling is going to be
pretty tricky and far more dangerous.

Fixes #3546
Allow the PHPCS to fail.
Fail the build as soon as one build fails.

No need to run all the builds when one of them has already failed.
Consistent use of `Shell::err` for errors
Merge pull request #3577 from tersmitten/consistent-use-of-err-for-errors

Consistent use of `Shell::err` for errors
Force .bat files to have CRLF endings.

Newer versions of git convert line endings on checkout. This also causes
these files to show up as always modified when the repo is cloned
because the index and working copy have different line endings.

Hopefully this fixes the issue.

Fixes #3585