3D board display: better rendering of the board: the board polygon outlines (generated by the specctra function) is now used to create the 3D body of the board.

Eeschema: better name for m_SheetList (changed to m_SheetPath) member of  class NETLIST_OBJECT.

*) add hotkey for setting the grid origin as 'S', in board editor, module editor.
*) re-position the function interface for cursor movement from BASE_SCREEN into
   class EDA_DRAW_FRAME.  This is a prelude to getting rid of BASE_SCREEN or
   splitting it up.

Replace in EDA_TEXT::Draw the parameter EDA_DRAW_PANEL* aPanel  by EDA_RECT* aClipBox, which is the actual parameter used by Draw.
This change make more easy to  use this function when a EDA_DRAW_PANEL canvas is not used to draw texts.
Remove dead code in worksheet.cpp.

   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.

(explanation: float is implicitly promoted to double anyway, it's only useful
for storage; also a fp variable forces conversion of other int in the expression
without needing a cast)
Typo fixes in some comments 'floatting' -> 'floating' :D

The plan goes like this:
- eeschema still uses int in decidegrees
- all the other things internally use double in decidegrees (or radians
  in temporaries)
- in pcbnew UI the unit is *still* int in decidegrees

The idea is to have better precision everywhere while keeping the user with int i
angles. Hopefully, if a fractional angle doesn't come in from the outside, everything
should *look* like an integer angle (unless I forgot something and it broke)

When the time comes, simply updating the UI for allowing doubles from the user should
be enough to get arbitrary angles in pcbnew.

New conversion routines and sin/cos implementation for angles in decidegrees

- Removed spurious int casts (these are truncated anyway and will break
  doubles)

- Applied the Distance, GetLineLength, EuclideanNorm, DEG2RAD, RAD2DEG
  ArcTangente and NORMALIZE* functions where possible

- ArcTangente now returns double and handles the 0,0 case like atan2, so
  it's no longer necessary to check for it before calling

- Small functions in trigo moved as inline

Fixed layer picker for exporting to pcbnew
Realigned pcb layer name with class BOARD

More layer classification cleanup

Better description for entities on right click menu and panel
Typo fixes and some comment reformats

Gerbview, layer manager: add option (popup menu) to always keep layers not visible but the active layer, even when the active layer is changed.
Pcbnew: fix swig warning for operator EDA_COLOR_T::++  (changed to function EDA_COLOR_T:: NextColor)

In particular the new mechanism for handling extended color palettes is in place,
included renaming the ini keys and saving the color name instead of its index; this means better forward compatibility with palette changes.

Since ini keys are changed, colors will be reset

Implemented the LAYER_NUM typedef (LAYER was already taken as a class name...) to represent a layer number.

- Renamed ReturnMaskLayer to GetLayerMask (since it's a plain getter)

added option to allow zooming around the crosshair instead of the center; can be enabled via options or by holding alt while using the mousewheel

Gerbview: Fix a minor but annoying issue in gerbview  config: colors setup is broken when running a testing version after an old gerbview version (due to a bug of this old version which breaks the color config)

* Improve MSG_PANEL_ITEM to handle message panel information.
* Create containers for passing message panel items between objects and
  the message panel.
* Rename EDA_ITEM::DisplayInfo to EDA_ITEM::GetMsgPanelInfo.
* Remove all direct manipulation of EDA_DRAW_FRAME from all objects derived
  from EDA_ITEM.

Pcbnew: board editor: allows pad edition by hotkey 'E' (was accessible only by mouse button right click)
All: minor code cleaning and very minor bug fixes.