* src/format.[Ch]

	* src/format.[Ch]
	(document_): new flag, telling whether this is a document format and
	we want to show this format in the export and view menus
	(documentFormat): accessor for document_

	* src/format.h: Add some documentation

	* src/frontends/qt3/QPrefsDialog.C
	(QPrefsDialog::QPrefsDialog): handle new documentCB checkbox
	(QPrefsDialog::switch_format): ditto
	(QPrefsDialog::updateFormatsButtons): ditto
	(QPrefsDialog::new_format): ditto
	(QPrefsDialog::modify_format): ditto

	* src/frontends/qt3/ui/QPrefFileformatsModule.ui: Add documentCB checkbox

	* src/frontends/qt4/QPrefsDialog.C
	(QPrefsDialog::QPrefsDialog): handle new documentCB checkbox
	(QPrefsDialog::switch_format): ditto
	(QPrefsDialog::updateFormatsButtons): ditto
	(QPrefsDialog::new_format): ditto
	(QPrefsDialog::modify_format): ditto

	* src/frontends/qt4/ui/QPrefFileformatsUi.ui: Add documentCB checkbox

	* src/frontends/xforms/FormPreferences.C
	(FormPreferences::Formats::build): handle new check_document checkbox
	(FormPreferences::Formats::input): ditto
	(FormPreferences::Formats::Add): ditto
	(FormPreferences::Formats::Browser): ditto

	* src/frontends/xforms/forms/form_preferences.fd: Add check_document
	checkbox

	* src/lyxrc.C
	(LyXRC::read): Remove compatibility code for 1.3 \format entries.
	Read the new format flags (but don't require them for 1.4
	compatibility)
	(LyXRC::write): Write the new format flags

	* src/MenuBackend.C
	(expandFormats): Remove the hardcoded exception for image formats
	and use Format::isDocument() instead

	* lib/doc/Customization.lyx: Document auto viever/editor and the
	"document format" flag

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@13887 a592a061-630c-0410-9148-cb99ea01b6c8