Eeschema, Modedit: void fields (mainly the footprint field) now cannot be selected when click on them.

Eeschema: fix issues in drag command (mainly hotkey command and forgotten wire ends connected to components to drag).
 Rename EDA_Rect::Inside to EDA_Rect::Contains ( EDA_Rect::Inside( const EDA_Rect& aRect ) was very ambiguous )
 Fix some Doxygen warnings and erroneous comments; Add comments.

DIR_LIB_SOURCE.  It only needs to be able to read Sweet strings quickly.
@todo: Change public API regarding part rev string.

    Completed a good portion of /new class DIR_LIB_SOURCE.
    Added an autonomous CMakeLists.txt file to /new, with new-docs target and
    test program target.

Gerbview: remove flicker when refresh screen. Pcbnew fix (partially) issue when printing in mirror mode ( version compiled  with USE_WX_ZOOM = ON specific). Minor enhancements.

Minor cosmetic enhancements.
commint forgoten files in boost lib.

    Added: in file dialog, multiple file selection.
    Added: Draw mode selector (in left toolbar):
        Raw mode:
            a Gerber image is drawn on screen without buffering.
            Artifacts happen if there are negative items drawn, if more than one
            Gerber file is shown.
        Stacked mode:
            each Geber image is drawn in a buffer and after drawn on screen
            No artifact with negative items.
            Each Gerber image covers previous images.
        OR mode (transparency mode):
            each Geber image is drawn in a buffer and after drawn on screen
            No artifact with negative items.
            Each Gerber image is "ORed" with previous images, like in Pcbnew.
    Try to optimize Draw function in buffered modes.
        (Useful for PC that have problems with "blit" graphic function)
    Fix minor issues.

    Added: in file dialog, multiple file selection.
    Added: Draw mode selector (in left toolbar):
        Raw mode:
            a Gerber image is drawn on screen without buffering.
            Artifacts happen if there are negative items drawn, if more than one  Gerber file is shown.
        Stacked mode:
            each Geber image is drawn in a buffer and after drawn on screen
            No artifact with negative items.
            Each Gerber image covers previous images.
        OR mode (transparency mode):
            each Geber image is drawn in a buffer and after drawn on screen
            No artifact with negative items.
            Each Gerber image is "ORed" with previous images, like in Pcbnew.
    Try to optimize Draw function in buffered modes.
        (Useful for PC that have problems with "blit" graphic function)
    Fix minor issues.

Fix Gerbview issue (does not display gerber images) when Gerbview is compiled with USE_WX_ZOOM defined.

Pcbnew: fix crash after displaying "The text thickness is too large for the text size. It will be clamped" when editing pcb text properties (Linux specfic)