Add colors to logging

This includes the bold as well.

INFO is just default, WARN is yellow, ERROR is red.

We try to automatically detect if the output is a TTY (and thus supports
colors), and don't emit colors if so. Windows 10 supports ANSI color
codes starting with a specific build, but we don't care to emit whatever
garbage Microsoft invented for builds older than that.

desktop_version/src/Vlogging.h

@@ -6,6 +6,8 @@ extern "C"
 {
 #endif
 
+void vlog_init(void);
+
 int vlog_info(const char* text, ...);
 
 int vlog_warn(const char* text, ...);