* to_upper/lower fully-compatible with Unicode
* utf8_no_index:
- * Add cache for the last indexed character
- * Two-way iteration
- * Intelligent indexed access (calculating the nearest point of insertion, i.e. begin, end, or cache)
+ * Add cache for the last indexed character - DONE
+ * Two-way iteration - DONE
+ * Intelligent indexed access (calculating the nearest point of insertion, i.e. begin, end, or cache) - DONE
+ * UnicodeChar as universal type
+ * UnicodeChar => Char and Char => Byte