Make abort" functional in interpret mode. This behavior is undefined

by ANS Forth standard, but it's useful.

Also, define the constant true in a more strict way. C might garantee
2-complement math, but Forth doesn't.

sys/boot/ficl/softwords/softcore.fr

@@ -31,20 +31,33 @@ decimal 32 constant bl
 
 : spaces  ( n -- )   0 ?do space loop ;
 
-: abort"  
-    postpone if 
-    postpone ." 
-    postpone cr 
-    -2
-    postpone literal
-    postpone throw 
-    postpone endif 
-; immediate 
+: abort"
+    state @ if
+        postpone if
+        [char] " parse
+        postpone sliteral
+        postpone type
+        postpone cr
+        -2
+        postpone literal
+        postpone throw
+        postpone endif
+    else
+	[char] " parse
+        rot if
+            type
+            cr
+            -2 throw
+	else
+	    2drop
+        then
+    then
+; immediate
 
 
 \ ** CORE EXT
-0  constant false 
--1 constant true 
+0 constant false
+false invert constant true
 : <>   = 0= ; 
 : 0<>  0= 0= ; 
 : compile,  , ;