List the missing channel modes in the 004 reply (closes #238)

The channel-modes parameter of RPL_MYINFO left out modes that each
transport's MODE accepts. The IRC listener now sends Himnostv, adding
H, i, o and v. The HTTP API now sends Hbiklmnostv, adding H, b and v.
Each transport keeps its own list, because they accept different
modes. The tests compare the whole parameter, so a missing or extra
mode fails them. The README and the schema notes show the new HTTP API
list.

Model: opus-5-5

schema/README.md

@@ -145,7 +145,7 @@ Where a schema file and the HTTP API disagree, the HTTP API is right:
 - `003.json` describes the server's creation date. The HTTP API sends the date
   the server last started.
 - `004.json` has example mode lists. The HTTP API sends `ow` as the user modes
-  and `ikmnostl` as the channel modes.
+  and `Hbiklmnostv` as the channel modes.
 - `322.json` says `LIST` gets one reply per channel. The server leaves out a
   secret channel, one with mode `+s`, unless the user is on it.
 - `332.json` says `RPL_TOPIC` answers a `TOPIC` query. The HTTP API has no such