Script API: remove 2048 length limit for the variadic text functions

[ivan-mogilko]

Historically, all the text printing script functions have a limit of resulting string. It was an arbitrary 3000 bytes around 3.6.0, in current master it's 2048, but that's not the point. Because AGS Strings may contain up to INT32_MAX bytes, there should not be any restriction on a length of a string that a user may create using e.g. String.Format.

Printing script args is done using ScriptSprintf function. I propose to fix this function to make it act in compliance with standard snprintf: that is let pass a null buffer in which case it would only calculate and return necessary size. Formatting will be done in two steps: first calculate the necessary buffer length, then allocate a StringBuffer, print text, and create ScriptString, or use this text elsewhere as necessary.

[ericoporto]

I was playing with this by looking into the function before I realized I don't know where the call to this is

ericoporto@5f485b1

Beyond the tests, I can't figure how this actually get called in String.Format, and don't know how to modify to take the null buffer, but maybe my initial sketch is useful?