Convenient str interpolation function for C++
It takes a string with special formatting symbols and generate a sequence of strings.
"/this/is/a/string[1-3].png" will give you a list of strings: "/this/is/a/string1.png", "/this/is/a/string2.png", "/this/is/a/string3.png"
###Format rules:
[1-3] -> 1,2,3
[01-03] -> 01, 02, 03
[01-03, 04, 05, 06-08] -> 01, 02, 03, 04, 05, 06, 07, 08