Better defensive programming to check column names in multiple_comparisons

[rogerssam]

If a column name is provided that is too similar to the output columns, multiple_comparisons() will change the names of all the columns between the first and the maximum matching column to factors.

See example code below:

# Any of these names will break the function
c("predicted.value", "std.error", "Df",
  "groups", "PredictedValue", "ApproxSE", "ci", "low", "up")
library(biometryassist)
dat <- design("crd", LETTERS[1:4], 4, nrow = 4, ncols = 4)$design
names(dat)[5] <- "groups"
dat$response <- rnorm(16, 10)
dat.aov <- aov(response~groups, data = dat)
multiple_comparisons(dat.aov, classify = "groups", trans = "log", offset = 0)