breakpoints are now treated like single character words

so that the can be HardWrapped and are not ignored.
According Test are added too.

wordwrap/wordwrap.go

@@ -198,7 +198,15 @@ func (w *WordWrap) Write(b []byte) (int, error) {
 			// valid breakpoint
 			w.addSpace()
 			w.addWord()
-			w.buf.WriteRune(c)
+			_, _ = w.word.WriteRune(c)
+
+			// Wrap line if the breakpoint would exceed the Limit
+			if w.HardWrap && w.lineLen+w.space.Len()+runewidth.RuneWidth(c) > w.Limit {
+				w.addNewLine()
+			}
+
+			// treat breakpoint as single character length words
+			w.addWord()
 		} else if w.HardWrap && w.lineLen+w.word.PrintableRuneWidth()+runewidth.RuneWidth(c)+w.space.Len() == w.Limit {
 			// Word is at the limite -> begin new word
 			w.word.WriteRune(c)

wordwrap/wordwrap_test.go

@@ -250,6 +250,15 @@ func TestHardWrap(t *testing.T) {
 			true,
 			"",
 		},
+		// hyphens have also to be hardwrapped
+		{
+			"------------------------------------",
+			"----\n----\n----\n----\n----\n----\n----\n----\n----",
+			4,
+			true,
+			true,
+			"",
+		},
 	}
 	for i, tc := range tt {
 		f := NewWriter(tc.Limit)