Equality comparisons between dates and times can take some extra time to
comprehend. I tend to think of a date or time as "before" or "after"
another date or time, but I naturally read `<` and `>` as "less than"
and "greater than." This change seeks to make date/time comparisons more
human readable.

This basically reverts 8da30ad6

This reverts commit 3420a145, reversing
changes made to afb66a5a.

Actually, private methods cannot be called with `self.`, so it's not just redundant, it's a bad habit in Ruby

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

This reverts commit 70d6e16f, reversing
changes made to ea4db3bc.

Seems to be a code merge done by mistake.

Added middle_of_day method to Date and DateTime

array

The behavior we had in place in rc1 was actually to convert to DateTime and use <=> from there. Restore that.

These warnings were actually a bug in Ruby 2.0, the accessors should not
be raising such warnings, they are only meant for ivars.

-

Revert "fix warnings in Ruby 2.0"

This reverts commit 26702a6d.

-

Revert "Merge pull request #8282 from arunagw/warning_removed_for_ruby2"

This reverts commit f63d6544, reversing
changes made to 3a890681.

The to_time_in_current_zone method doesn't match the naming of the methods
for converting to ActiveSupport::TimeWithZone on Time and DateTime. Since
DateTime inherits from Date that has led to confusion with some users
using the to_time_in_current_zone method with DateTime instances and having
the time part dropped and the UTC offset lost.

This commit fixes this by deprecating the old method and adding a new
in_time_zone method which matches the naming for DateTime and Time. This
should prevent accidently dropping times and UTC offsets when converting
DateTime instances to ActiveSupport::TimeWithZone.

Date.beginning_of_week thread local and beginning_of_week application config option added (default is Monday)

* Added the `DateAndTime::Calculations` module that is included in Time
  and Date. It houses common calculations to reduce duplicated code.
* Simplified and cleaned-up the calculation code.
* Removed duplication in tests by adding a behavior module for shared
  tests. I also added some missing tests.

Unnecessary peace of text was injected at
507da04a by mistake.

core extensions

There are a bunch of other implicit branches that adds
1.8.x specific code that still needs to be removed. Pull
requests for those cases are welcome.

A recent change to beginning_of_week and end_of_week added an argument
that can be used to specify the week's starting day as a symbol. Now
these methods were aliased as monday and sunday respectively which as a
consequence of the argument addition, made calls like obj.monday(:sunday)
possible. This commit makes them methods on their own.

beginning_of_week extended in both Time and Date so that to return week start based on start day that is monday by default