adjusted some addresses, added more stubs

c64/basic/a453.interop

@@ -0,0 +1,3 @@
+
+This routine is probably used by many cartridges and other software to initialize parts of the system. At least the UCart uses it - see here:
+- https://www.elektroda.pl/rtvforum/topic3293027.html

c64/basic/a453.unknown.s

@@ -0,0 +1,4 @@
+
+// XXX provide documentation and implementation
+
+    STUB_IMPLEMENTATION()

c64/basic/a644.interop

@@ -0,0 +1,3 @@
+
+This routine is probably used by many cartridges and other software to initialize parts of the system. At least the UCart uses it - see here:
+- https://www.elektroda.pl/rtvforum/topic3293027.html

c64/basic/a644.new.s

@@ -0,0 +1,5 @@
+
+// XXX provide documentation and real implementation
+
+new:
+    STUB_IMPLEMENTATION()

c64/basic/init/basic_warm_start_internal.s

@@ -1,6 +1,9 @@
-// Clear screen etc, show READY prompt.
 
-basic_warm_start:
+//
+// Continuation of the BASIC cold start routine
+//
+
+basic_warm_start_real:
 
 #if CONFIG_MEMORY_MODEL_60K
 	// We need our helpers to get to filenames under ROMs or IO area
@@ -8,6 +11,7 @@ basic_warm_start:
 #endif
 
 	// If warm start caused by BRK, print it address
+	// XXX sys 58235 also triggers this - to be fixed
 	lda CMP0
 	ora CMP0+1
 	beq !+

c64/basic/init/e3b7.basic_warm_start.jmp.s

@@ -0,0 +1,5 @@
+// Clear screen etc, show READY prompt.
+
+basic_warm_start:
+
+	jmp basic_warm_start_real

c64/basic/init/e3b7.interop

@@ -0,0 +1,5 @@
+
+This is a well-known address, needed even for some BASIC programming - it's a common target for a SYS command. See for example here:
+
+- http://ready64.org/articoli/_files/043_pokesc64.txt
+  sys 58235 - Warm Start