Initial Pcbnew s-expression file format commit.

* Add s-expression Format() function to all objects derived from
  BOARD_ITEM.
* Add s-expression Format() function to base objects as required.
* Add functions to convert coordinates from base internal units
  (nanometers) to millimeter string for writing to s-expression
  file.
* Add temporary dummy conversion functions to prevent link errors
  until schematic and board object and action code can be separated
  into DSO/DLL.
* Add CMake build option to build Pcbnew with nanometer internal
  units.

common/base_struct.cpp

@@ -32,6 +32,7 @@
 #include <trigo.h>
 #include <common.h>
 #include <macros.h>
+#include <kicad_string.h>
 #include <wxstruct.h>
 #include <class_drawpanel.h>
 #include <class_base_screen.h>
@@ -223,6 +224,14 @@ EDA_ITEM& EDA_ITEM::operator=( const EDA_ITEM& aItem )
 }
 
 
+void EDA_ITEM::Format( OUTPUTFORMATTER* aFormatter, int aNestLevel, int aControlBits ) const
+    throw( IO_ERROR )
+{
+    wxFAIL_MSG( wxString::Format( wxT( "Format method not defined for item type %s." ),
+                                  GetChars( GetClass() ) ) );
+}
+
+
 #if defined(DEBUG)
 
 // A function that should have been in wxWidgets
@@ -546,6 +555,85 @@ wxString EDA_TEXT::GetTextStyleName()
 }
 
 
+bool EDA_TEXT::IsDefaultFormatting() const
+{
+    return (  ( m_Size.x == DEFAULT_SIZE_TEXT )
+           && ( m_Size.y == DEFAULT_SIZE_TEXT )
+           && ( m_Attributs == 0 )
+           && ( m_Mirror == false )
+           && ( m_HJustify == GR_TEXT_HJUSTIFY_CENTER )
+           && ( m_VJustify == GR_TEXT_VJUSTIFY_CENTER )
+           && ( m_Thickness == 0 )
+           && ( m_Italic == false )
+           && ( m_Bold == false )
+           && ( m_MultilineAllowed == false ) );
+}
+
+
+void EDA_TEXT::Format( OUTPUTFORMATTER* aFormatter, int aNestLevel, int aControlBits ) const
+    throw( IO_ERROR )
+{
+    aFormatter->Print( aNestLevel, "(text %s (at %s",
+                       EscapedUTF8( m_Text ).c_str(), FormatBIU( m_Pos ).c_str() );
+
+    if( m_Orient != 0.0 )
+        aFormatter->Print( aNestLevel, "%0.1f", m_Orient );
+
+    aFormatter->Print( aNestLevel, ")\n" );
+
+    if( !IsDefaultFormatting() )
+    {
+        aFormatter->Print( aNestLevel+1, "(effects\n" );
+
+        if( ( m_Size.x != DEFAULT_SIZE_TEXT ) || ( m_Size.y != DEFAULT_SIZE_TEXT ) || m_Bold
+          || m_Italic )
+        {
+            aFormatter->Print( aNestLevel+2, "(font" );
+
+            // Add font support here at some point in the future.
+
+            if( ( m_Size.x != DEFAULT_SIZE_TEXT ) || ( m_Size.y != DEFAULT_SIZE_TEXT ) )
+                aFormatter->Print( aNestLevel+2, " (size %s)", FormatBIU( m_Size ).c_str() );
+
+            if( m_Bold )
+                aFormatter->Print( aNestLevel+2, " bold" );
+
+            if( m_Bold )
+                aFormatter->Print( aNestLevel+2, " italic" );
+
+            aFormatter->Print( aNestLevel+1, ")\n");
+        }
+
+        if( m_Mirror || ( m_HJustify != GR_TEXT_HJUSTIFY_CENTER )
+          || ( m_VJustify != GR_TEXT_VJUSTIFY_CENTER ) )
+        {
+            aFormatter->Print( aNestLevel+2, "(justify");
+
+            if( m_HJustify != GR_TEXT_HJUSTIFY_CENTER )
+                aFormatter->Print( aNestLevel+2,
+                                   (m_HJustify == GR_TEXT_HJUSTIFY_LEFT) ? " left" : " right" );
+
+            if( m_VJustify != GR_TEXT_VJUSTIFY_CENTER )
+                aFormatter->Print( aNestLevel+2,
+                                   (m_VJustify == GR_TEXT_VJUSTIFY_TOP) ? " top" : " bottom" );
+
+            if( m_Mirror )
+                aFormatter->Print( aNestLevel+2, " mirror" );
+
+            aFormatter->Print( aNestLevel+2, ")\n" );
+        }
+
+        // As of now the only place this is used is in Eeschema to hide or show the text.
+        if( m_Attributs )
+            aFormatter->Print( aNestLevel+2, "hide" );
+
+        aFormatter->Print( aNestLevel+1, "\n)\n" );
+    }
+
+    aFormatter->Print( aNestLevel, ")\n" );
+}
+
+
 /******************/
 /* Class EDA_RECT */
 /******************/