Make wxLogInfo() work even without wxLog::SetVerbose()

It's confusing that wxLogInfo() and wxLogVerbose() are exactly the same and
the former, and not only the latter, doesn't do anything unless SetVerbose()
had been called, even if the log level is wxLOG_Info or higher.

Fix this by checking for GetVerbose() in wxLogVerbose() only and making
wxLogInfo() check the log level only. This makes it very similar to
wxLogMessage() but this is not such a bad thing.

Also improve wxLogVerbose() documentation.

interface/wx/log.h

@@ -1261,9 +1261,31 @@ void wxVLogMessage(const char* formatString, va_list argPtr);
 /** @addtogroup group_funcmacro_log */
 //@{
 /**
-    For verbose output. Normally, it is suppressed, but might be activated if
-    the user wishes to know more details about the program progress (another,
-    but possibly confusing name for the same function could be @c wxLogInfo).
+    For low priority messages.
+
+    They are handled in the same way as messages logged by wxLogMessage() by
+    the default logger but could be handled differently by the custom loggers.
+
+    @header{wx/log.h}
+*/
+void wxLogInfo(const char* formatString, ... );
+void wxVLogInfo(const char* formatString, va_list argPtr);
+//@}
+
+/** @addtogroup group_funcmacro_log */
+//@{
+/**
+    For verbose output.
+
+    Messages generated by these functions are suppressed by default, even if
+    the log level is higher than ::wxLOG_Info and need to be explicitly
+    activated by calling wxLog::SetVerbose().
+
+    Notice that this is done automatically by wxWidgets, unless the standard
+    command line handling is overridden, if @c --verbose option is specified on
+    the program command line, so using these functions provides a simple way of
+    having some diagnostic messages not shown by default but which can be
+    easily shown by the user if needed.
 
     @header{wx/log.h}
 */