Remove unnecessary require from active_support/inflector/methods.rb

`active_support/inflections` already requires
`active_support/inflector/inflections`. There's no need to require it in
`active_support/inflector/methods`.
change to destructive `deep_symbolize_keys` after https://github.com/rails/rails/commit/df24b8790f22384a068fece7042f04ffd2fcb33e which allows to do so. This helps to avoid extra hash object creation, by symbolizing inplace
make "rails dbconsole" work with activerecord-postgis-adapter
Add test for AR::CounterCache.update_counters
Refactor AR's counter_cache_test.rb test
Use Range#cover? for Numeric ranges (tests via endpoints) and use Range#include? for non-numeric ranges

added changelog message
Remove OracleDatabaseTasks was deprecated, because this was provided by 3rd-party.
Remove SqlseverDatabaseTasks was deprecated, because this was provided by 3rd-party.
Remove FirebirdDatabaseTasks was deprecated, because this was provided by 3rd-party.
Added a warning about #1769 to the routing guide.
Use symbols instead of strings

ActiveSupport::Concern is used all over Rails
This PR will only create 3 new objects as keys are never recreated and
are not subject to garbage collection.

The strings were being uniquely created and garbage collected. I don't
have any performance numbers but this should be better than all of the
GC.
Merge pull request #142 from codyrobbins/master

Added a warning about #1769 to the routing guide
more guidelines for command line
`existant` => `existent`
replace version 3.2.3 by 4.0.0.beta in command line
`dasboard` => `dashboard`
date_field docs for action view
Change "." to ":" for formatting purpose
Merge pull request #151 from vatrai/action_view_basic

date_field docs for action view
Merge pull request #146 from vatrai/command_line_rake_guid

more guidelines for rake tasks