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.

* Fix offset errors when scale factor greater is than one.
* Changed behavior of fit in page when not drawing border and
  title block to fit board outline in page.
* Fix offset errors when mirroring (still not 100% correct on MSW with
  wxWidgets 2.9.4).
* Lots of the usual code cleaning and simplifying.

MacOSX: disabling BufferedBitmap of OSX in gerbview, not supported nor accelerable and bitmap becomes too large in case of retina display to be usable

All: remove macros  MAX, MIN, ABS from macros.h and replace these macros by std::max, std::min and std::abs (mainly found in old code).

switch all <math.h> includes to <cmath> includes on an attempt to dodge some abiguous references to atan2()

Other minor fixes.

Code cleaning, minor fixes and minor coding style fixes. wxWidgets 2.9.4 compatibility fix( deprecated function MakeModal )

Pcbnew: automatic selection of plugin when loading a file with .kicad_pcb extension from history list.
Very minor other fixes

Because this bug could create bad values in footprint libraries, this parameter is now checked
when reading a footprint description in legacy format

Eeschema (also Libedit and Libview) starts always to the default grid (50 mils)
Gerbview starts with the last selected grid, but the validity is tested.
In Pcbnew the grid value is always displayed, so it should always be good.

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.

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.