Internal unit improvements and Pcbnew s-expression file format changes.

* Move EDA_TEXT object into separate header and source file.
* Compile EDA_TEXT class separately for BOARD_ITEM and SCH_ITEM units.
* Compile PAGE_INFO  class separately for BOARD_ITEM and SCH_ITEM units.
* Minor formatting tweaks to Pcbnew s-expression file.
* Move internal unit formatting functions into BOARD_ITEM and SCH_ITEM.

bitmap2component/bitmap2cmp_gui.cpp

@@ -427,17 +427,3 @@ bool EDA_APP::OnInit()
 void EDA_APP::MacOpenFile(const wxString &fileName)
 {
 }
-
-
-
-
-/**
- * @copydoc
- *
- * This is a dummy since KiCad doesn't perform any interal unit formatting.
- */
-/** @todo Remove FormatBIU() when the common DSO/DSL code is implemented. */
-std::string FormatBIU( int aValue )
-{
-    return "";
-}