[ci skip] Updated create! documentation description and added +attributes+ for rdoc
Tables existence check query is executed in large quantities

When Rails starts, tables existence check query is executed
number of models.
In case of mysql,

    SHOW TABLES LIKE 'table1';
    SHOW TABLES LIKE 'table2';
    SHOW TABLES LIKE 'table3';
    ...
    SHOW TABLES LIKE 'table999';

Add process to get the names of all tables by one query.
Fix spelling.
Merge pull request #16422 from tgxworld/fix_spelling

Closes #16422
change to empty? from blank?
Merge pull request #16421 from tsukasaoishi/prevant_manycall_showtables

Tables existence check query is executed in large quantities
use the uri parser so that newer version of Ruby work
remove dead file_watcher code
Merge pull request #16424 from gregors/remove_dead_code

remove dead file_watcher code
defer running after_config hooks until after the object is allocated
add a new constructor that runs load hooks
need to call super
Stop using padding in the generated Gemfile -- it looks shit
Merge branch 'master' of github.com:rails/rails
Pull spring gem entry into the Gemfile template instead of gemfile_entries so it can be grouped with the other development tools
Merge pull request #16384 from tomkadwill/improved_create_documentation

[ci skip] Added +object+ and +attributes+ to create! description for rdoc
Rephrase how we explain RecordInvalid exception in the context of
`#create!` regarding validations in contrast to the behavior of
`#create`. Also describe creating multiple objects using an array of
hashes as the +attributes+ parameter. [ci skip] /cc #16384
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