Add json_object_get_numkey().
Add json_array_get_string_safe().

Yes, I'm not too happy about the name.
Add basic Music Room comment patching.
Add strings_get().

Yeah, it's just a one-liner, but it keeps the stringdefs object local to the strings module. I really don't want to have it end like the runconfig again, where we have lots of direct accesses to its values all across the code.
Add strings_sprintf().

This originally resulted from some confusion about the th14 spell card practice menu not properly working with strings_vsprintf(), but didn't really help anything.

And now, we do want it again for Music Room patching.