data: one trie for maps and dictionaries, one loader

The hash map served a single exact-match lookup that the trie already
answers, at the price of a second container, a second file loader with
its own drift, and a Str-to-UTF-8 conversion on every chain probe. The
files are small (kanji.dict is 7.5k lines), so the trie holds both.
trieopen validates keys and each space-separated value word against Str
and reports path:line; trielookup takes the Str every caller holds and
treats a nil trie as an unloaded map; trienew/trieput exist for tests.
The overflow guards on growth, Trie.root (always 0) and the per-language
init loop written twice are gone.

main.c

@@ -58,8 +58,7 @@ threadmain(int argc, char **argv)
 	keyc = chancreate(sizeof(Keyreq), 0);
 	dictreqc = chancreate(sizeof(Dictreq), 4);
 	dictresc = chancreate(sizeof(Dictres), 0);
-	mapinit(argv[1]);
-	dictinit(argv[1]);
+	langinit(argv[1]);
 	srvinit();
 	proccreate(drawthread, nil, 16384);
 	proccreate(srvthread, nil, 16384);