Define interfaces for inline call handlers and BRK

Instead of providing no-op CheckJsr/CheckJsl, plugins now declare
which calls they support by defining interfaces on the plugin class.

I added a CheckBrk call for code like Apple /// SOS calls, which
use BRK as an OS call mechanism.  The formatting doesn't work quite
right yet because I've been treating BRK as a two-byte instruction.
Hardly anything else does, and I think it's time I stopped (but not
in this commit).

Note: THIS BREAKS ALL PLUGINS that use the inline JSR/JSL feature,
which is pretty much all of them.

SourceGen/RuntimeData/Apple/GSOS.cs

@@ -34,7 +34,7 @@ using PluginCommon;
 */
 
 namespace RuntimeData.Apple {
-    public class GSOS : MarshalByRefObject, IPlugin {
+    public class GSOS : MarshalByRefObject, IPlugin, IPlugin_InlineJsl {
         private const string GSOS_FUNC_TAG = "AppleIIgs-GSOS-Functions";  // tag used in .sym65 file
         private bool VERBOSE = false;
 
@@ -58,11 +58,6 @@ namespace RuntimeData.Apple {
             mFunctionList = PlatSym.GenerateValueList(platSyms, GSOS_FUNC_TAG, appRef);
         }
 
-        public void CheckJsr(int offset, out bool noContinue) {
-            // Not used by GS/OS
-            noContinue = false;
-        }
-
         public void CheckJsl(int offset, out bool noContinue) {
             noContinue = false;
             if (offset + 7 < mFileData.Length && mFileData[offset + 1] == 0xa8 &&