Lua tag lists

Index and take length of tag lists like a table, 1-indexed. There are three
methods which may be used on tag lists:

list:iterate() - returns an iterator over the tags in the list
list:has(tag) - returns a boolean whether the tag is in the list
list.shares(list2) - returns whether two lists share a tag

"find" is also an alias to "has". Each method may be accessed from the global
taglist library too, e.g. taglist.iterate(list)

Tag lists may be compared with an equality operator too. This will tell you if
the two lists are composed of identical tags.

Accessible from sector.taglist, line.taglist and mapthing.taglist.