Added unicode support

Replaced strings with rune-slices, which capture unicode codepoints more
accurately.

misc.go

@@ -22,7 +22,7 @@ func dotChars() []rune { // Returns all possible characters represented by the d
 }
 
 // Returns true if str[idx] and str[idx-1] are separated by a word boundary.
-func isWordBoundary(str string, idx int) bool {
+func isWordBoundary(str []rune, idx int) bool {
 	str_runes := []rune(str)
 	wbounded := idx == 0 ||
 		idx >= len(str) ||