Very minor fixes: add missing const return type to some GetBoundingBox() declarations. Change few functions names to better names in some places (like GetName() to GetPinName() )

They are now member of EDA_DRAW_FRAME.
This change could fix Bug #1330781 (Background color change in Eeschema affects background color in Pcbnew)
Show page limits has meaning only for the schematic editor,  the board editor and the page layout editor.
Draw background color selection exists only in eeschema and  page layout editor.
In pcbnew, only a black background is allowed.
A side effect is now the user should set the background color in schematic editor, and the library editor (2 different options).
The default is still the white color.

   File "rules" has instructional text as comments near top.

2) Convert all text files in repo to LF line ending form.
   Any checkout done with "rules" in play will convert the working
   tree to native line ending, while keeping repo as LF line ending.

Add include/dialog_shim.h and common/dialog_shim.cpp for use by wxformbuilder's "subclass a wxDialog" support.
This works, but in my version of wxformbuilder there is a bug which does not properly show the 
subclass property, even though it is still in play.  This happens after saving then loading the *.fbp file.
So it is a nuisance bug, but does not affect functionality.