Check if a key is in VariTAS options
in.varitas.options(option.name = NULL, varitas.options = NULL,
nesting.character = "\\.")String giving name of option (with different levels joined by nesting.character)
Ampliseq options as a list. If missing, they will be obtained from get.varitas.options()
String giving Regex pattern of nesting indication string. Defaults to '\.'
in.options Boolean indicating if the option name exists in the current varitas options