Document cJSON_free API

Add json-patch/json-patch-tests for testing JSON patch implementation

This allows checking for leading zeroes and invalid characters after the index

This was completely broken, arrays weren't accepted.

git-subtree-dir: tests/json-patch-tests
git-subtree-split: 716417e71e328e116dc1e98b903b434578bc1a1c

cJSON_Compare

Two NULL strings should not be considered equal for the purpose of
cJSON.

Fixing all /W4 level warnings.

This can reduce worst case peak memory usage by 30% depending on the
realloc implementation.