reimplement vi's '$' motion as a DFA, also eliminating a bug that involves double deleteion in the process

fcore/cursor-dfa/vi-dlr-dfa.sml

@@ -0,0 +1,56 @@
+structure ViDlrDfa =
+struct
+  val startState: Word8.word = 0w0
+  val newlineState: Word8.word = 0w1
+  val notNewlineState = 0w2
+
+  fun makeStart i =
+    if Char.chr i = #"\n" then newlineState else notNewlineState
+
+  val startTable = Vector.tabulate (255, makeStart)
+  val newlineTable = startTable
+  val notNewlineTable = startTable
+
+  val tables = #[startTable, newlineTable, notNewlineTable]
+
+  fun isFinal currentState = currentState = newlineState
+
+  structure ViDlr =
+    MakeNextDfaLoop
+      (struct
+         val startState = startState
+
+         structure Folder =
+           MakeCharFolderNext
+             (struct
+                val startState = startState
+                val tables = tables
+
+                fun finish x = x - 1
+                val isFinal = isFinal
+              end)
+
+         val fStart = Folder.foldNext
+       end)
+
+  structure ViDlrForDelete =
+    MakeNextDfaLoop
+      (struct
+         val startState = startState
+
+         structure Folder =
+           MakeCharFolderNext
+             (struct
+                val startState = startState
+                val tables = tables
+
+                fun finish x = x + 1
+                val isFinal = isFinal
+              end)
+
+         val fStart = Folder.foldNext
+       end)
+
+  val next = ViDlr.next
+  val nextForDelete = ViDlrForDelete.next
+end