proposal: support empty string as separator for string_to_array

Hello

I have one idea, that should simplify string to char array
transformation. The base is idea: between every char is empty string,
so empty string is regular separator for string_to_array function.
This behave is inversion of array_to_string function behave:

postgres=# select array_to_string(array['a','b','c'],'');array_to_string
-----------------abc
(1 row)

postgres=# select string_to_array('abc','');string_to_array
----------------- {a,b,c}
(1 row)

Notes, ideas???

Regards
Pavel Stehule