Bring back some performance, on VteBench, we get 58% throughput boost and on the

raw feeding test we get 20%, unclear to me why the same data on different tests
produces such wild results, but I will take it.

Author: migueldeicaza

Sources/SwiftTerm/Utilities.swift

@@ -312,7 +312,8 @@ struct UnicodeUtil {
 
     /**
      * Number of column positions of a wide-character code.   This is used to measure runes as displayed by text-based terminals.
-     * - Returns: The width in columns, 0 if the argument is the null character, -1 if the value is not printable, otherwise the number of columsn that the rune occupies.
+     * - Returns: The width in columns, 0 if the argument is the null character,
+     *   -1 if the value is not printable, otherwise the number of columsn that the rune occupies.
      * - Parameter rune: a UnicodeScalar
      */
     static func columnWidth (rune: UnicodeScalar) -> Int
@@ -322,7 +323,16 @@ struct UnicodeUtil {
         if irune == 0 {
             return 0
         }
-        if irune < 0x20 || (irune >= 0x7F && irune <= 0xA0) {
+	// control characeters return -1
+        if irune < 0x20 {
+            return -1
+        }
+	// ascii letters use one column
+        if irune < 0x7f {
+            return 1
+        }
+	// more non-printable characters
+        if irune <= 0xA0 {
             return -1
         }