#67 - Fix methods index() and index_n()

Completed.

Author: schmouk

cpp-strings/cppstrings.h

@@ -249,23 +249,22 @@ class CppStringT : public std::basic_string<CharT>
     * \see index_n(), rindex() and rindex_n().
     * \see find(), find_n(), rfind() and rfind_n().
     */
-    inline constexpr size_type index_n(const CppStringT& sub, const size_type start, const size_type length) const
+    inline constexpr size_type index_n(const CppStringT& sub, const size_type start, const size_type count) const
     {
-        return index_n(sub, start, start + length - 1);
+        return index(sub, start, start + count - 1);
     }
 
     /** Like find_n(sub, start), but raises NotFoundException when the substring is not found.
     *
     * \see index_n(), rindex() and rindex_n().
     * \see find(), find_n(), rfind() and rfind_n().
     */
-    inline constexpr size_type index_n(const CppStringT& sub, const size_type length) const
+    inline constexpr size_type index_n(const CppStringT& sub, const size_type count) const
     {
-        return index_n(sub, 0, length - 1);
+        return index(sub, 0, count - 1);
     }
 
 
-
     //---   is_punctuation()   --------------------------------
     /** \brief Returns true if the string contains only one character and if this character belongs to the ASCII punctuation set. */
     inline const bool is_punctuation() const noexcept