Conditional layer generation support

In this patch, I made a new layer generation method as following example. This patch will allow people who want a conditional design rule as if metal1 is wider than something, the spacing must be ...

define RDS_ALU1 min_width 5.0 -> WIDE_ALU1; caracterise WIDE_ALU1 ( regle 1000 : width < 7. ; ); undefine WIDE_ALU1;

Also, I corrected 'resize' syntax of define rule and now it is usable.

define RDS_ALU1 -1.0 resize -> CHNG_ALU1;