A very fast version of kin::to[xxx].
Finds out where a tiddler originates from, is it in a tag tree with xxx as root?
See demo site for interactive examples.
[[Ling]in-tagtree-of[Clancy]] : check if Ling is ''in a tag tree'' with Clancy as root.
[all[tiddlers]!in-tagtree-of[Clancy]] : with ! prefix, get all tiddlers that are ''not'' in a tag tree with Clancy as root.
[all[tiddlers]in-tagtree-of:inclusive[Clancy]] : with inclusive suffix, get all tiddlers that are ''in a tag tree'' with Clancy as root, ''including Clancy himself''