Add wxDateSpan::GetTotalMonths() method.

This is similar to the existing GetTotalDays() and counts both months and
years.

See #14704.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72615 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -535,7 +535,7 @@ All:
 - Fix compilation of wxHash{Map,Set} with g++ 4.7 (Nathan Ridge).
 - Fix posting large amounts of data in wxHTTP (Platonides).
 - Add wxFile::ReadAll() for consistency with wxFFile.
-- Add wxDateTime::DiffAsDateSpan() (jonasr).
+- Add wxDateTime::DiffAsDateSpan() and wxDateSpan::GetTotalMonths() (jonasr).
 - Added Nepali translation (Him Prasad Gautam).
 
 All (GUI):

include/wx/datetime.h

@@ -1579,6 +1579,8 @@ public:
     int GetYears() const { return m_years; }
         // get number of months
     int GetMonths() const { return m_months; }
+        // returns 12*GetYears() + GetMonths()
+    int GetTotalMonths() const { return 12*m_years + m_months; }
         // get number of weeks
     int GetWeeks() const { return m_weeks; }
         // get number of days

interface/wx/datetime.h

@@ -1703,6 +1703,16 @@ public:
     */
     int GetMonths() const;
 
+    /**
+        Returns the combined number of months in this date span, counting both
+        years and months.
+
+        @see GetYears(), GetMonths()
+
+        @since 2.9.5
+    */
+    int GetTotalMonths() const;
+
     /**
         Returns the combined number of days in this date span, counting both
         weeks and days. This doesn't take months or years into account.