* Create new GEDA PCB plug in.
* Add support for opening GEDA PCB footprints with module editor.
* Make import footprint file dialog remember last selected footprint
type during current session.
* Update module editor file import to use new GEDA PCB plug in.
* Let IO_MGR know about GEDA PCB plug in.
* Create a WHITESPACE_FILTER_READER to simplify parsing GEDA PCB footprint
files.
their type, by using the more abstract PLUGIN::Footprint*() functions.
This is an intermediate phase only, other changes will be necessary as library table support comes in.
Encapsulate usage of library path searching, since that will go away as library table support comes in.
Add FOOTPRINT_EDIT_FRAME::{get,set}LibPath() and FOOTPRINT_EDIT_FRAME::{get,set}LibNickName() functions
to provide this encapsulation.
* Move board item object Format() functions into PCB_IO object.
* Change file format to use layer names instead of numbers.
* Change file extension to kicad_pcb.
* Save dialog now supports saving boards to new file format.
* Add CMake option to build s-expression file save.
* Add check to main CMakeList.txt file to make sure nanometers are
enables when the new file format is built.
* Minor tweaks to object format functions for improved output.
* Rename kicad_plugin.h/cpp to legacy_plugin.h/cpp.