Get the name to search for, for a root_name declared as import in ini

Property definitions

nitc :: loader $ MPackage :: import_alias
	# Get the name to search for, for a `root_name` declared as `import` in `ini`
	fun import_alias(root_name: String): nullable String
	do
		var map = import_aliases_parsed
		if map == null then return null

		var val = map.get_or_null(root_name)
		if val == null then return null

		return val.dir_name
	end
src/loader.nit:1204,2--1214,4