Fix issue when using a page layout file in project folder: eeschema and Pcbnew did not use it, unless using an absolute path.
Now, if the file path is nor absolute, it is seen as relative to the project (which is the expected behavior)
fp lib wizard: when pcbnew id compiled with USE_GITHUB_PLUGIN=OFF, the github plugin option is no more accessible (and the web viewer no more used).
* 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
Dick Hollenbeck
Wayne Stambaugh
Alexander Zakamaldin