sequences: Remove start for real in favor of subseq-start.

Update a usage of start that was masked by the ALIAS:

Compatibility/migration is a .99 feature.

basis/bootstrap/compiler/compiler.factor

@@ -89,7 +89,7 @@ gc
     "." write flush
 
     {
-        member-eq? split harvest sift cut cut-slice start index clone
+        member-eq? split harvest sift cut cut-slice subseq-start index clone
         set-at reverse push-all class-of number>string string>number
         like clone-like
     } compile-unoptimized

core/sequences/sequences.factor

@@ -985,9 +985,6 @@ PRIVATE>
 
 : subseq-start ( subseq seq -- i ) 0 subseq-start-from ; inline
 
-ALIAS: start subseq-start
-ALIAS: start* subseq-start-from
-
 : subseq? ( subseq seq -- ? ) subseq-start >boolean ;
 
 : drop-prefix ( seq1 seq2 -- slice1 slice2 )