Update semantic shortcuts

Update BKeymap::GetModifiedCharacters() to translate a given character
and set of modifiers filling out a list of all characters that match for another
set of modifiers.

This allows us to, for example, get all characters in the normal map that
have the '+' character in the corresponding shift map.

It is fully generic allowing one to get a list of characters in any map given
a character and modifiers of another map.

Also I converted from using a BList to using a BObjectList.

With this, along with BWindow::HasShortcut(), the semantic shortcuts now
work not only with Command+'=', but any key in the normal map that has
'+' in it's shift map as long as it isn't already taken by another shortcut.

headers/private/shared/Keymap.h

@@ -12,10 +12,9 @@
 
 #include <DataIO.h>
 #include <InterfaceDefs.h>
+#include <ObjectList.h>
 
 
-class BList;
-
 class BKeymap {
 public:
 								BKeymap();
@@ -40,9 +39,9 @@ public:
 			void				GetChars(uint32 keyCode, uint32 modifiers,
 									uint8 activeDeadKey, char** chars,
 									int32* numBytes) const;
-			status_t			GetModifiedCharacters(const char* normal,
-									int32 modifiers,
-									BList* _modifiedCharacters);
+			status_t			GetModifiedCharacters(const char* in,
+									int32 inModifiers, int32 outModifiers,
+									BObjectList<const char>* _outList);
 
 			const key_map&		Map() const { return fKeys; }