Make BDateFormat inherit from BFormat again

* Move relevant parts up into BFormat so other format classes can use
those
* Adjust BDurationFormat and BTimeUnitFormat for the changes
* Remove the "default" date format, it is better to keep only a default
locale and let applications create B*Formats from it as needed.
* Creating a B*Format without arguments to the constructor now
configures it for the default locale, which allows for easy use in
standard cases (formatting something with the current language and
format)
* Creating a B*Format is potentially an expansive operation, it is
advised to keep the instance around and reuse it whenever possible.
However it must be "refreshed" when the locale changes, for apps which
supports that, since it keeps a copy of the language and formatting
convention, rather than a pointer to the locale as it did before.

headers/os/locale/DateFormat.h

@@ -28,18 +28,15 @@ enum BWeekday {
 };
 
 
-class BDateFormat {
+class BDateFormat: public BFormat {
 public:
-								BDateFormat(const BLanguage* const,
-									const BFormattingConventions* const);
+								BDateFormat(
+									const BLanguage* const language = NULL,
+									const BFormattingConventions* const
+										format = NULL);
 								BDateFormat(const BDateFormat &other);
 	virtual						~BDateFormat();
 
-	static	const BDateFormat*	Default();
-
-			void				SetLanguage(const BLanguage& newLanguage);
-			void				SetFormattingConventions(
-									const BFormattingConventions& conventions);
 			status_t			GetDateFormat(BDateFormatStyle style,
 									BString& outFormat) const;
 			void				SetDateFormat(BDateFormatStyle style,
@@ -73,9 +70,6 @@ private:
 			icu::DateFormat*	_CreateDateFormatter(
 									const BString& format) const;
 
-	mutable	BLocker				fLock;
-			BFormattingConventions	fConventions;
-			BLanguage			fLanguage;
 };
 
 

headers/os/locale/DurationFormat.h

@@ -7,6 +7,7 @@
 
 
 #include <Format.h>
+#include <Locale.h>
 #include <String.h>
 #include <TimeUnitFormat.h>
 
@@ -31,7 +32,7 @@ public:
 
 			void				SetSeparator(const BString& separator);
 
-	virtual	status_t			SetLocale(const BLocale* locale);
+	virtual	status_t			SetLanguage(const BLanguage& language);
 			status_t			SetTimeZone(const BTimeZone* timeZone);
 
 			status_t			Format(bigtime_t startValue,

headers/os/locale/Format.h

@@ -6,6 +6,9 @@
 #define _B_FORMAT_H_
 
 #include <FormatParameters.h>
+#include <FormattingConventions.h>
+#include <Locker.h>
+#include <Language.h>
 #include <SupportDefs.h>
 
 
@@ -40,18 +43,25 @@ class BLocale;
 
 class BFormat {
 public:
-			status_t			InitCheck() const;
+			status_t				SetLocale(const BLocale& locale);
+	virtual	status_t				SetLanguage(const BLanguage& newLanguage);
+	virtual	status_t				SetFormattingConventions(
+										const BFormattingConventions&
+											conventions);
 
-	virtual	status_t			SetLocale(const BLocale* locale);
+			status_t				InitCheck() const;
 protected:
-								BFormat();
-								BFormat(const BFormat& other);
-	virtual 					~BFormat();
+									BFormat();
+									BFormat(const BFormat& other);
+	virtual 						~BFormat();
 
-			BFormat&			operator=(const BFormat& other);
+			BFormat&				operator=(const BFormat& other);
 
-			status_t			fInitStatus;
-			BLocale*			fLocale;
+protected:
+	mutable	BLocker					fLock;
+			BFormattingConventions	fConventions;
+			BLanguage				fLanguage;
+			status_t				fInitStatus;
 };
 
 

headers/os/locale/LocaleRoster.h

@@ -79,7 +79,6 @@ public:
 									// (that needs to link with liblocalestub.a)
 
 			const BLocale*		GetDefaultLocale() const;
-			const BDateFormat*	GetDefaultDateFormat() const;
 
 			bool				IsFilesystemTranslationPreferred() const;
 

headers/os/locale/TimeUnitFormat.h

@@ -46,7 +46,7 @@ public:
 
 			BTimeUnitFormat&	operator=(const BTimeUnitFormat& other);
 
-	virtual	status_t			SetLocale(const BLocale* locale);
+	virtual	status_t			SetLanguage(const BLanguage& locale);
 			status_t			Format(int32 value, time_unit_element unit,
 									BString* buffer,
 									time_unit_style style = B_TIME_UNIT_FULL