default order clause (fixes #5103)

A callable object passed as a constraint for a route may access the request
parameters as part of its check. This causes the combined parameters hash
to be cached in the environment hash. If the constraint fails then any subsequent
access of the request parameters will be against that stale hash.

To fix this we delete the cache after every call to `matches?`. This may have a
negative performance impact if the contraint wraps a large number of routes as the
parameters hash is built by merging GET, POST and path parameters.

Fixes #2510.

Adding proc evaluation for action caching layout parameter

Enable ActionDispatch::Http::Headers to support fetch

* save original exception
* keep original backtrace

Refactored remove_column

Gem const presence checking has been removed

Rakefile executable attributes and shebang lines has been removed

ActionPack routes: remove some useless code.

Fix build for railties generators 

build fix for SharedGeneratorTests

BigDecimal string wrapping in JSON serialization can now be opted-out

Remove tests for undocumented private methods

Use new hash syntax in generated Gemfile

Build fix for plugin new generator change

Related to a06a84bf

gemspec assumes that user kept all generated files

Removing unused local vars in Queue tests

JSON: encode BigDecimal NaN/Infinity as null.

delete_all raise an error if a limit is provided - fixes #4979