Introduce a "font-tranform" property

[JulNadeauCA]

To specify a general transformation matrix in agar css.

For example, to render text 1/3 condensed: font-transform: [ 0.333, 0.0, 1.0, 0.0 ] or render 12 degrees oblique: font-transform: [ 1.0, 0.207, 1.0, 0.0 ]