Clarification of device parameter compare on LVS required

[klayoutmatthias]

Currently the following behavior is unintuitive:

Specifying tolerances on a device class will make all other parameters ignored. This is a bit unexpected. Parameters for which no tolerance is given, should still be compared.

Futhermore, it's not possible to disable parameters as using "enable_parameters" with false will make the parameters still being compared: currently a parameter is compared if it is primary in either the schematic or layout netlist. So disabling is effective only if a parameter is disabled in both the schematic and layout netlist. This is a bit tedious.

One option was to skip the "secondary/primary" parameter scheme and let users specify "ignore" as a valid "tolerance" to include or exclude parameters, e.g.

tolerance("RES", "W", relative: 1e-5)
tolerance("RES", "L", relative: 1e-5)
tolerance("RES", "R", ignore)   # do not compare "R" parameter