Short version string output

This adds support for just showing the version string
without the full welcome message if the log level is
less than the default. That means that you pass -q once
and you will just see "1.4.5".

This makes it easier to parse in scripts.

programs/zstdcli.c

@@ -544,6 +544,11 @@ static unsigned parseCompressionParameters(const char* stringPtr, ZSTD_compressi
 
 static void printVersion(void)
 {
+    if (g_displayLevel < DISPLAY_LEVEL_DEFAULT) {
+        DISPLAYOUT("%s\n", ZSTD_VERSION_STRING);
+        return;
+    }
+
     DISPLAYOUT(WELCOME_MESSAGE);
     if (g_displayLevel >= 3) {
     /* format support */