Keep debugger support only for rubies < 2.0.0
Update Gemfile templates to provide correct debugger
Update debugging guide to use byebug
Add a failing test for a URL helper that was broken by a6b9ea2.
Isolate debugger related code
Prevent generation of extra whitespace in templates
Fix error for aggregate methods with select, see issue #13648
docs, make association `autosave: true` examples runnable. Closes #14700

[ci skip]

The examples are written in a way you expect them to be executable.
However one snippet assumed there to be two comments when only one
was created above.

The defined models did not extend `ActiveRecord::Base`

The example used `comments.last.mark_for_destruction`. This does no
longer load the whole collection but just the last record. It is
then refetcht on subsequent calls to `last`. This breaks the example.
Minor fixes in the rails debugging guide
PostgreSQL, adapter automatically reloads it's type map. Closes #14678.

[Yves Senn & Matthew Draper]
PostgreSQL, warn once per connection per missing OID. Closes #14275.

[Yves Senn & Matthew Draper]
Implement fuzzy matching for route search on routing error html page.
Improve CSS styling for routing error html page.
Split search results into 'exact matches' and 'fuzzy matches'.

- also refactored the javascript.
Only make deeply nested routes shallow when parent is shallow

Since `:shallow` may be set at any point in the resource nesting we should
only make the new and collection routes shallow when the parent is shallow.

This is a bit of a hack but until the mapper is refactored to an object graph
instead of a hash of merged values it's the best we can do.

Fixes #14684.
Merge pull request #14684 from Futurelearn/jc-deep-nested-shallow-url-helper-bug

Add a failing test for a URL helper that was broken by a6b9ea2.
Re-review the debugging guide.

Tested on a brand new app to exactly match current byebug's behaviour.
Add more test case for #demodulize, Improve documentation
Merge pull request #14705 from akshay-vishnoi/doc_changes

Add more test case for #demodulize, Improve documentation
Move assets precompile (and version) to an initializer

sprockets-rails 2.1 needs the precompile list to be available in all
environments.