Remove useless wx/wx.h include, that create sometimes compil warnings on msys.

wx/wx.h includes all wxWidgets .h files, and sometimes creates collision
names in #define between kicad and windows headers
Moreover, blindly including a lot of useless files is compil time consuming

bitmap2component/bitmap2cmp_gui.cpp

@@ -35,6 +35,11 @@
 #include <wildcards_and_files_ext.h>
 #include <wx/clipbrd.h>
 #include <wx/rawbmp.h>
+#include <wx/filedlg.h>
+#include <wx/rawbmp.h>
+#include <wx/msgdlg.h>
+#include <wx/dcclient.h>
+
 
 #include "bitmap2cmp_gui_base.h"