#546 moonlib/mknob fix for pd-vanilla

[electrickery]

The moonlib/mknob objects uses the t_iem_init_symargs->x_reverse struct element
inside the t_iemgui struct. This element appears to be pd-extended only, as
the object will not build against pd-vanilla (0.46.6) headers. Loading the
object in a pd-vanilla environment will probably result in undesired behaviour.

The x_reverse is set in mknob_check_minmax as the result of (x->x_min > x->x_max)
and used only in mknob_set. By moving the "min > max" check to mknob_set, the
x->x_gui.x_isa.x_reverse can be eliminated, and pd-vanilla compatibility restored.

[Antoine Rousseau]

This issue has been fixed in latest moonlib 0.3.1 : https://github.com/MetaluNet/moonlib
now downloadable trough deken for linux & osx.