Should allow Pcbnew code easier to change and Gerbview code more understandable and easier to maintain.
Code cleaning (remove dead code, add comments).
Minor other enhancements.

Fix some warning compil issues.
Add zlib sources to avoid build issues under Windows (zlib not installed with mingw).

Add patch from Lorenzo Marcantonio. Fix some warning issues, and zlib issue under Windows (zlib sources added)

to Kicad from other EDA tools.

  edif2kicad        / EDIF to EEschema schematic import
    Tools with EDIF out writer:
       o OrCad
       o DataXpress
       o Viewlogic
       o IntuSoft ICAP
       o Protel nVisage
       o PADS ?
       o P-CAD ?
       o EDIF viewer (www.cimmetry.com)
       o EDIF translator (www.elgris.com/content/edif_overview.html)

  pcb123net2kicad   / converts a pcb123 netlist to Kicad default format

generation tool.  For now, it is just an s-expression beautifier using
our "non-specctra mode" version of s-expressions.

All: change MILS_TO_IU_SCALING_FACTOR constant to IU_PER_MILS ( and MM_TO_IU_SCALING_FACTOR to IU_PER_MM)
Also fix bug 985654.

All: change MILS_TO_IU_SCALING_FACTOR constant to IU_PER_MILS ( and MM_TO_IU_SCALING_FACTOR to IU_PER_MM)
Also fix bug 985654.

All: change MILS_TO_IU_SCALING_FACTOR constant to MILS_PER_IU  ( and  MM_TO_IU_SCALING_FACTOR to MM_PER_IU)
Also fix bug 985654.

Other scaling factors (MILS_TO_IU_SCALING_FACTOR and DECIMILS_TO_IU_SCALING_FACTOR)
also defined only in convert_to_biu.h.
Allows different scaling value for Gerbview.
Needs more tests.

solution to see that it was not pre-computing constants when used in static initializers.

So we have two use cases, and need two solutions to be optimal, since the compiler 
is too stupid to do the right thing.

I think we need something else for compile time computable constants, to be optimal 
in both use cases.  There is quite a bit of code savings by using a macro for that 
situation from my testing.  To fully capitalize on this, we need to go back and make 
Mm2mils() and what not macros also, or have MACRO versions of them too.

  as a starting point
* Make double Distance() take double arguments and remove internal range checking.
* Start on EDA_DRAW_FRAME::AdjustScrollBars() and use "double" for most all calculations
  in anticipation of setting INT_MAX INT_MIN limits eventually.

* 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.

// This provides better project control over rounding to int from double
// than wxRound() did.  This scheme provides better logging in Debug builds
// and it provides for compile time calculation of constants.


#include <stdio.h>
#include <assert.h>
#include <limits.h>

//-----<KiROUND KIT>------------------------------------------------------------

/**
 * KiROUND
 * rounds a floating point number to an int using
 * "round halfway cases away from zero".
 * In Debug build an assert fires if will not fit into an int.
 */

#if defined( DEBUG )

// DEBUG: a macro to capture line and file, then calls this inline

static inline int KiRound( double v, int line, const char* filename )
{
    v = v < 0 ? v - 0.5 : v + 0.5;
    if( v > INT_MAX + 0.5 )
    {
        printf( "%s: in file %s on line %d, val: %.16g too ' > 0 ' for int\n", __FUNCTION__, filename, line, v );
    }
    else if( v < INT_MIN - 0.5 )
    {
        printf( "%s: in file %s on line %d, val: %.16g too ' < 0 ' for int\n", __FUNCTION__, filename, line, v );
    }
    return int( v );
}

#define KiROUND( v )    KiRound( v, __LINE__, __FILE__ )

#else

// RELEASE: a macro so compile can pre-compute constants.

#define KiROUND( v )  int( (v) < 0 ? (v) - 0.5 : (v) + 0.5 )

#endif


//-----</KiROUND KIT>-----------------------------------------------------------

// Only a macro is compile time calculated, an inline function causes a static constructor
// in a situation like this.
// Therefore the Release build is best done with a MACRO not an inline function.
int Computed = KiROUND( 14.3 * 8 );


int main( int argc, char** argv )
{
    for( double d = double(INT_MAX)-1;  d < double(INT_MAX)+8;  d += 2.0 )
    {
        int i = KiROUND( d );

        printf( "t: %d  %.16g\n", i, d );
    }

    return 0;
}

*) for footprint access into *.mod files and 
*) BOARD save/load

The item_io.cpp and ioascii.cpp have been set off to the side for reference
as *.notused, for awhile.

The CMake options USE_NEW_PCBNEW_LOAD and USE_NEW_PCBNEW_SAVE are gone,
this is now the mandatory usage of the LEGACY_PLUGIN.  This should reduce
code maintenance for awhile until the s-expression plugin comes into 
play.  But at least for legacy format, there is not two code bodies
to maintain any more.

A new LEGACY_PLUGIN footprint library caching scheme is in place which 
needs some testing.  It should not be any faster, but might give better 
results in a networked environment if there is *.mod files on the server.

* Remove internal units from BASE_SCREEN and it's derivatives.
* Remove internal units from EDA_DRAW_FRAME and it's derivatives.
* Use build time code to replace internal units conversions.
* Fix scaling bug in page layout sample window that I created in my
  last commit.

* Move all convert from user to internal units into base_units.cpp.
* Remove internal units parameters from all moved conversion functions.
* Revise all source code that calls the moved conversion functions.
* Remove internal units from all dialog text control helper classes.

Kicad manager: code cleaning. Dead code removed and minor fixes. support of new .kicad_brd extension.

* Scale page reference border and title block, grid sizes, and zoom factors
  correctly for nanometers.

Other minor fixes.

* Move all convert from internal to user units functions into separate file.
* Remove internal units parameter from all moved conversion functions.
* Revise all source code that calls the moved conversion functions.
* Compile these conversion routines separately for the appropriate pcb or
  schematic internal units.
* Move internal units specific status bar update code into the appropriate
  application for updating the status bar.
* Move millimeter user units rounding function to common.cpp.

drawframe.cpp: commit a fix about scrollbars  from lajos kamocsay