* 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.
* 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.
Jean-Pierre Charras
Wayne Stambaugh
Alexander Zakamaldin
Dick Hollenbeck