Remove metadata option

[g1o]

If there is a duplicated metadata or an extra column in it there is no way to remove or modify the elements. This means that if you save an object with wrong metadata, you have to redo every step to generate another without the wrong metadata or extra column.

library(pagoo)
toy_rds <- system.file('extdata', 'campylobacter.RDS', package = 'pagoo')
a<-load_pangenomeRDS(toy_rds)
a$organisms$country<-NULL

# Error in (function ()  : 
#   unused argument (base::quote(new("DFrame", rownames = c("1", "2", "3", "4", "5", "6", "7"), nrows = 7, listData = list(1:7, 
#   c("FR15", "FR27", "AR1", "AR8", "AR12", "CA1", "TW6"), c("2008/170h", "2012/185h", "99/801", "04/875", "06/195", "001A-
#  0374", "1830"), c(2008, 2012, 1999, 2004, 2006, 2005, 2008), c("Human", "Human", "Bovine", "Bovine", "Bovine", "Human", 
#  "Human"), c("Feces", "Blood", "Prepuce", "Fetus", "VM", "Blood", "Blood"), c("ERS672247", "ERS672259", "ERS739235", 
#  "ERS739242", "ERS739246", "ERS686652", "ERS739261")), elementType = "ANY", elementMetadata = NULL, metadata = 
#  list())))