Parse and sniff MIME types the way browsers do, by the MIME Sniffing
Standard.

A MIME type is a plain map:

- :type and :subtype, in lower case, e.g. "text" and "html"
- :parameters, when there are any, a map of lower-case names to values
  in the order of the text

The parameters can also be a vector of name-value pairs. Unlike the map,
it keeps its order when you add a ninth parameter.

Every function that takes a MIME type also takes its text, and treats
text that doesn't parse as nil.

The byte patterns of the MIME Sniffing Standard, and the functions that
match them against the first bytes of a resource.

The bytes are a byte array on the JVM and a Uint8Array in ClojureScript
(a Node Buffer is one). Only the first 1445 count, so a whole body will
do. A function returns a MIME type as text, e.g. image/png, or nil when
nothing matches.

A row of a table is a map of:

- :pattern, the bytes to match, with :tt for a space or > after a tag
- :mask, how much of each byte counts: all of it for 0xFF, all but the
  case of a letter for 0xDF, and none of it for 0x00
- :ignored, the bytes that may come before the pattern
- :type, the MIME type of a match