* Encapsulate most of the MODULE class.
* Start encapsulating the DIMENSION class.
* Lay some groundwork for EDA_TEXT encapsulation.
* Move cleverly hidden MODULE functions into class_module.cpp.
* Use std::swap to exchange TEXTE_PCB values for undo/redo.
* Remove unused members from MODULE class.
* The usual coding policy and documentation fixes.
* Add s-expression file parser object and keyword files.
* Fix minor issues with s-expression file formatting.
* Fix a minor bug the zone container fill state parsing in the legacy plugin.
* Move EDA_TEXT visibility definition to eda_text.h.
* Add minor BOARD_ITEM object improvements to support s-expression file
parser.
* 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.