Fix two problems with one commit:

1. The I18N_ARGUMENT_MISSING that appears when moving or resizing one
window. The problem happens because when declaring the variables
myResizeString, myCoordString[0] and myCoordString_[1] i18nc tries to
replace %1, %2, %3, and %4, but those arguments are not passed here.
Using #define we avoid the argument passsage.

2. Replace QString::arg() with direct formating, which is better for
performance.

I know we should avoid #define but in this case I think it is the best
option. If anyone has a better alternative feel free to change this
commit.