Because on windows MachineInfo take a little time to init, we make it to
a singleton.
MachineInfo is build the first time in main.cpp.
Now all other places where we use MachineInfo (aboutqetdialog and
configdialog) gui don't hang anymore in waiting to MachineInfo finish to
build.
Instead of build machine_info class which take time, only to get the max
width and height of screens, call of methods
Machine_info::i_max_screen_width() and
Machine_info::i_max_screen_height() are now static and compute only
this.
The project properties dialog is now faster because don't wait the end
build of machine_info.
**Break a lot of thing.**
This reverts commit 1db1800572aa9a636b0cc03cd70cb490e47f00ca, reversing
changes made to 4c563821e885535ec123a019b5aa545e729b6cfc.
