Fixes to TestCaseTest.
Retrieve source code for the entire stack trace

Provide the ability to extract the source code of the entire exception stack
trace, not just the frame raising the error. This improves debugging
capability of the error page, especially for framework-related errors.
Update actionpack CHANGELOG
[ci skip] Changed 'first argument' to '+name+ argument'
Merge pull request #16428 from tomkadwill/activerecord_associations_name_param

[ci skip] Changed 'first argument' to '+name+ argument'
Fix typo in plugins doc
Merge pull request #16430 from guillermo/patch-1

Fix typo in plugins doc
Fix the #const_regexp's documentation [ci skip]

Originally introduced in f9086d63, the documentation of this method is
wrong as #const_regexp returns a string to easy the interpolation inside
regular expressions.
Merge pull request #16426 from tgxworld/fix_false_positive

Fixes to TestCaseTest.
Merge pull request #16427 from ryandao/full_stack_source_extract

Full stack source extract