NLTK: Symlink-based arbitrary file read in IPIPANCorpusReader, bypasses nltk.pathsec entirely

Summary IPIPANCorpusReader nltk/corpus/reader/ipipan.py exposes public methods, channels, domains, categories, and fileidschannels=..., that accept a caller supplied fileids list and read a file via a completely unprotected builtin open call, with no nltk.pathsec involvement at all. A symlink...