Fix wierd ConfigBaseWriteDouble's Printf( wxT("%12f"), aValue ); format string

which was creating silly strings like 

  PcbTextThickness="    0.300000"

in kicad.pro files.

common/projet_config.cpp

@@ -19,8 +19,20 @@
 #include <boost/foreach.hpp>
 
 
-#define CONFIG_VERSION 1
-#define FORCE_LOCAL_CONFIG true
+#define CONFIG_VERSION      1
+#define FORCE_LOCAL_CONFIG  true
+
+
+void ConfigBaseWriteDouble( wxConfigBase* aConfig, const wxString& aKey, double aValue )
+{
+    // Use a single strategy, regardless of wx version.
+    // Want C locale float string.
+
+    LOCALE_IO   toggle;
+    wxString    tnumber = wxString::Format( wxT( "%.16g" ), aValue );
+
+    aConfig->Write( aKey, tnumber );
+}
 
 
 bool EDA_APP::ReCreatePrjConfig( const wxString& fileName,

include/param_config.h

@@ -15,28 +15,14 @@
 
 
 /**
- * inline ConfigBaseWriteDouble
- * This is a helper funvtion tor write doubles in config
+ * Function ConfigBaseWriteDouble
+ * This is a helper function to write doubles in config
  * We cannot use wxConfigBase->Write for a double, because
  * this function uses a format with very few digits in mantissa,
  * and truncation issues are frequent.
  * We use here a better floating format.
- *
- * Note: prior to 2.9.1, the separator was localized, and after, uses
- * the "C" notation
  */
- void inline ConfigBaseWriteDouble( wxConfigBase* aConfig,
-                                    const wxString& aKey, double aValue )
- {
-    wxString tnumber;
-
-#if wxCHECK_VERSION(2,9,1)
-    tnumber = wxString::FromCDouble( aValue, 12 );
-#else
-    tnumber.Printf( wxT("%12f"), aValue );
-#endif
-    aConfig->Write( aKey, tnumber );
-}
+void ConfigBaseWriteDouble( wxConfigBase* aConfig, const wxString& aKey, double aValue );
 
 
 /** Type of parameter in the configuration file */