Provide facility for large arrays to be output over long multiple lines

When you have a large array (let's say 1000 integers) that needs to be written out, it will be written out one int per line. It would be very useful to be able to specify how many items (or a max line length) are output per line to improve formatting and remove the need for a lot of CR's

e.g, with a max items per line of 10

{
"array" :
[
0,1,2,3,4,5,6,7,8,9
10,11,12,13,14,15,16,17,18,19
20,21,22,23,24,25,26,27,28,29
],
}

Start by locating jsoncpp's array serialization and line-breaking logic; the issue names no file, test, or entry point. Clarify whether formatting should use a maximum item count, maximum line length, or both, then add coverage that demonstrates the requested multiline output for large arrays.