The 'wrapper' accessibility handler is now ignored if a menu item has a
custom component, and has no submenu, and cannot be triggered
automatically. This avoids the case where a custom menu item may end up
with a wrapper accessibility handler that has no useful actions.

This patch also adds a 'label' argument to the addCustomItem functions,
which allows text for the screen reader to be supplied in the case where
a custom component is in use, but the menu item has accessibility
actions.

This commit removes the various compiler-specific JUCE_DEPRECATED macros and replaces them with C++14's deprecated attribute. It also removes the JUCE_CATCH_DEPRECATED_CODE_MISUSE flag as we can rely on the override specifier catching usage of these old virtual methods, and tidies up the DOXYGEN preprocessor checks as they were inconsistent across the codebase.

See BREAKING-CHANGES.txt for more details.

Adds a new `drawPopupMenuBackgroundForOption` member function to
`PopupMenu::LookAndFeelMethods`. By default this will pass through
to `drawPopupMenuBackground`, but it can be overridden in cases
where the background appearance depends on the current `Options`.