better compatibility with wxWidgets 2.9. Markers enhancement in pcbnew (right click can display marker info)

Added load error dialog. To display file load errors in a wxTextCtrl with a message, this is the BUG 2802441 enhancement

in bezier_curves: changed  calculations like dx*dx to (double)dx * dx to avoid integer overflow in calculation

* Added modified version of FindwxWidgets.cmake to prevent manifest build and link errors
  with VC8.
* Fixed ambiguous math function ( sqrt, atan, cos, etc. ) call errors when building
  with MSVC.
* Moved bitmap copy bitmap source file destination to the build path to prevent source
  tree pollution and library rebuilds when building on different platforms.

Pcbnew: fixed a recent bug that could be creates errors in rats nest calculations (forgotten rats nets)

Eeschema: code cleaning

some cleanup.

Now uses only an unique default pen size for plot/print and draw items (see changelog)

* Applied sheet reference plotting patch from Lorenzo.
* Fixed bug in Pcbnew plot dialog, ignore user scaling when controls are disabled.

Minor others changes.