obs-ffmpeg, UI: Allow slash in recording names

Automatically generate directories if slashes are present in a recording
name format set in advanced settings or in the replay buffer
prefix/suffix settings.

Fixes obsproject/obs-studio#2416
Closes obsproject/obs-studio#2858

UI/window-basic-main-outputs.cpp

@@ -837,8 +837,7 @@ bool SimpleOutput::StartStreaming(obs_service_t *service)
 
 static void remove_reserved_file_characters(string &s)
 {
-	replace(s.begin(), s.end(), '/', '_');
-	replace(s.begin(), s.end(), '\\', '_');
+	replace(s.begin(), s.end(), '\\', '/');
 	replace(s.begin(), s.end(), '*', '_');
 	replace(s.begin(), s.end(), '?', '_');
 	replace(s.begin(), s.end(), '"', '_');