Remove seemingly outdated lme4 note

[fweber144]

This removes a note concerning lme4::mkNewReTrms()'s argument re.form whose behavior seems to have been changed (fixed) in lme4 v1.1-38 (in that version, re.form <- re.form %||% reOnly(formula(object)) was added at the beginning of lme4::mkNewReTrms()). For now, I am not changing the call to lme4::mkNewReTrms() which is directly underneath that note because users might have an older version of lme4 installed and because adapting this call to the installed lme4 version would be overkill (the current call continues to work independent of the lme4 version because we don't rely on re.form = NULL but specify re.form explicitly).

Btw, R CMD check currently says:

checking R code for possible problems [...] NOTE
  plot.vsel: no visible global function definition for ‘packageVersion’
  plot.vsel: no visible binding for global variable ‘fontsize’
  Undefined global functions or variables:
    fontsize packageVersion
  Consider adding
    importFrom("utils", "packageVersion")
  to your NAMESPACE file.

which is probably due to commit 6e0682d (PR #556). I guess that needs to be fixed before a new CRAN release.

[aloctavodia]

Thanks. I am merging this as the failing tests are unrelated to the PR.