It's been long overdue that this variable be named properly. 2.2 added
integer scaling mode (thanks Ethan), 2.3 renamed it to scaling mode. Now
2.4 will properly call it what it is so people won't be confused by it.
The ScreenSettings struct member is renamed from stretch to scalingMode
along with the Screen class member being renamed, as well as the
toggleStretchMode function being renamed to toggleScalingMode as well.
Unfortunately, due to compatibility, we can't change the <stretch> XML
tag.
Apparently in C, if you have `void test();`, it's completely okay to do
`test(2);`. The function will take in the argument, but just discard it
and throw it away. It's like a trash can, and a rude one at that. If you
declare it like `void test(void);`, this is prevented.
This is not a problem in C++ - doing `void test();` and `test(2);` is
guaranteed to result in a compile error (this also means that right now,
at least in all `.cpp` files, nobody is ever calling a void parameter
function with arguments and having their arguments be thrown away).
However, we may not be using C++ in the future, so I just want to lay
down the precedent that if a function takes in no arguments, you must
explicitly declare it as such.
I would've added `-Wstrict-prototypes`, but it produces an annoying
warning message saying it doesn't work in C++ mode if you're compiling
in C++ mode. So it can be added later.
