Minor Bug: matlist objects can have duplicate labels

[billdenney]

This is related to #690 and #691.

It seems like the labels attribute of matlist objects should be required to be globally unique. In the example below, any(duplicated(unlist(new_omegalist@labels))) should be required to be FALSE. If something like #691 is accepted, then I think it should become an error for them to be duplicated, and if that path is not chosen, then I think it should become a warning to alert the user that they have probably done something unintentional.

library(mrgsolve)
#> 
#> Attaching package: 'mrgsolve'
#> The following object is masked from 'package:stats':
#> 
#>     filter
new_omegalist <- c(omat(house()), omat(house()))
new_omegalist
#> $...
#>         [,1] [,2] [,3] [,4]
#> ECL:       0    0    0    0
#> EVC:       0    0    0    0
#> EKA:       0    0    0    0
#> EKOUT:     0    0    0    0
#> 
#> $...
#>         [,1] [,2] [,3] [,4]
#> ECL:       0    0    0    0
#> EVC:       0    0    0    0
#> EKA:       0    0    0    0
#> EKOUT:     0    0    0    0
dput(new_omegalist)
#> new("omegalist", data = list(... = structure(c(0, 0, 0, 0, 0, 
#> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), .Dim = c(4L, 4L), .Dimnames = list(
#>     c("1: ", "2: ", "3: ", "4: "), NULL)), ... = structure(c(0, 
#> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), .Dim = c(4L, 4L
#> ), .Dimnames = list(c("1: ", "2: ", "3: ", "4: "), NULL))), n = c(4L, 
#> 4L), labels = list(c("ECL", "EVC", "EKA", "EKOUT"), c("ECL", 
#> "EVC", "EKA", "EKOUT")))

^{Created on 2020-06-16 by the reprex package (v0.3.0)}

[kylebaron]

Thanks, Bill. There is a check in the model object that will stop you if you create duplicate labels. But that's downstream of the matlist object. I'll put the check in place for the validity check for that object.

[kylebaron]

Formally addressed in #747