Fix serialization of control expressions with line breaks

[Filoppi]

The control expression editor allows line breaks, but the serialization was losing anything after the first line break (/r /n).

Instead of opting to encode them and decode them on serialization,
which I tried but was not safe, as it would lose \n written in the expression by users,
I opted to replace them with a space, to at least maintain some of the spacing the user originally put in.
Completely removing them could also have caused the expression to be parsed differently.
This cannot cause any breaking differences on the expression, and its in any way better than before, as before part of the string could just get lost.

[AdmiralCurtiss]

Why not just do the classic string escaping and escape \ using \\?

[Filoppi]

Why not just do the classic string escaping and escape \ using \\?

If the user writes \n for some reason in the expression (I don't think \ is an accepted operator for now, but it might be in the future), that will be serialized as \\n in the config.
If we also serialize any line break as \\n in the config, when we deserialize, we will need to turn every \\n into an \n again, effectively losing (and changing) the \n users had willingly put in the the expression for other reasons (not to get a line break).

[iwubcode]

I know very little about this code but I'm also confused. I don't see why we can't just serialize the exact string the user provides and deserialize the exact string the user provides.

Then it just becomes a parsing problem (no different whether they load from save or type something in).

[Filoppi]

I know very little about this code but I'm also confused. I don't see why we can't just serialize the exact string the user provides and deserialize the exact string the user provides.

Then it just becomes a parsing problem (no different whether they load from save or type something in).

You can't serialize actual line breaks in a dolphin config. Every config is just one line. Or so it seems.

[jordan-woyak]

Implementing typical backslash escaping will break current configs with device names containing a backslash unless the escaping is implemented at the expression parser level.

The real problem is our ini-file code being bad. It shouldn't be the job of input code to escape newlines so the config can be saved.
I think this is a good enough fix that can be easily removed if ini-files are ever fixed/removed.