Convert aliases monday and sunday to methods

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.

activesupport/lib/active_support/core_ext/date/calculations.rb

@@ -190,9 +190,14 @@ class Date
     result = self - days_to_start
     acts_like?(:time) ? result.midnight : result
   end
-  alias :monday :beginning_of_week
   alias :at_beginning_of_week :beginning_of_week
 
+  # Returns a new +Date+/+DateTime+ representing the start of this week. Week is
+  # assumed to start on a Monday. +DateTime+ objects have their time set to 0:00.
+  def monday
+    beginning_of_week
+  end
+
   # Returns a new +Date+/+DateTime+ representing the end of this week. Week is
   # assumed to start on +start_day+, default is +:monday+. +DateTime+ objects
   # have their time set to 23:59:59.
@@ -201,9 +206,14 @@ class Date
     result = self + days_to_end.days
     self.acts_like?(:time) ? result.end_of_day : result
   end
-  alias :sunday :end_of_week
   alias :at_end_of_week :end_of_week
 
+  # Returns a new +Date+/+DateTime+ representing the end of this week. Week is
+  # assumed to start on a Monday. +DateTime+ objects have their time set to 23:59:59.
+  def sunday
+    end_of_week
+  end
+
   # Returns a new +Date+/+DateTime+ representing the given +day+ in the previous
   # week. Default is +:monday+. +DateTime+ objects have their time set to 0:00.
   def prev_week(day = :monday)

activesupport/lib/active_support/core_ext/time/calculations.rb

@@ -174,9 +174,14 @@ class Time
     days_to_start = days_to_week_start(start_day)
     (self - days_to_start.days).midnight
   end
-  alias :monday :beginning_of_week
   alias :at_beginning_of_week :beginning_of_week
 
+  # Returns a new +Date+/+DateTime+ representing the start of this week. Week is
+  # assumed to start on a Monday. +DateTime+ objects have their time set to 0:00.
+  def monday
+    beginning_of_week
+  end
+
   # Returns a new Time representing the end of this week, week starts on start_day (default is :monday, i.e. end of Sunday).
   def end_of_week(start_day = :monday)
     days_to_end =  6 - days_to_week_start(start_day)

railties/guides/source/active_support_core_extensions.textile

@@ -3051,7 +3051,7 @@ d.end_of_week                # => Sun, 09 May 2010
 d.end_of_week(:sunday)       # => Sat, 08 May 2010
 </ruby>
 
-+beginning_of_week+ is aliased to +monday+ and +at_beginning_of_week+. +end_of_week+ is aliased to +sunday+ and +at_end_of_week+.
++beginning_of_week+ is aliased to +at_beginning_of_week+ and +end_of_week+ is aliased to +at_end_of_week+.
 
 h6. +prev_week+, +next_week+
 
@@ -3276,8 +3276,10 @@ The class +DateTime+ is a subclass of +Date+ so by loading +active_support/core_
 <ruby>
 yesterday
 tomorrow
-beginning_of_week (monday, at_beginning_of_week)
+beginning_of_week (at_beginning_of_week)
 end_of_week (at_end_of_week)
+monday
+sunday
 weeks_ago
 prev_week
 next_week
@@ -3450,8 +3452,9 @@ ago
 since (in)
 beginning_of_day (midnight, at_midnight, at_beginning_of_day)
 end_of_day
-beginning_of_week (monday, at_beginning_of_week)
+beginning_of_week (at_beginning_of_week)
 end_of_week (at_end_of_week)
+monday
 weeks_ago
 prev_week
 next_week