Fix `type` function to work better

Stop using getopt to parse flags. It's far more expensive than
necessary, and results in long flags not being parsed on OS X. This also
allows args starting with - after the options list to be properly
interpreted as a value to test.

Print the error message to stderr as is appropriate.

Use the new `command -p` functionality when the -a flag has not been
provided (`command` does not have any equivalent to the -a flag),
instead of using `which`. This is faster and also avoids any possible
disagreement between `which` and what fish thinks is valid.

Stop testing every path to see if it's executable, that test has already
been done by `which` or `command -p`.

The end result is `type -P ls` is roughly 250% faster, according to
profiling, on my OS X machine.
type: Separate the notion of multi and paths

Track whether -a and -f have been supplied separately. That way both
`type -a -f command` and `type -f -a command` behaves correctly, as does
`type -a -f foo` where there are multiple executables named `foo` in the
$PATH.
test: Add a new --quiet flag to suppress output

The --quiet flag is useful when only the exit status matters.

Fix the documentation for the -t flag to no longer claim that `type` can
print "keyword", as it never does that.

Stop printing a blank line for functions/builtins when the -p flag has
been passed. It's just not useful.
Adopt the new type -q flag in the other functions
type: Stop claiming `grep` is a function

Use `functions -q` instead of searching the `functiosn -na` list for the
provided word. This may result in an automatically-loaded function being
sourced, but that happens anyway with the default output.

This change means the results of `test -q foo` can be relied upon to
indicate whether `foo` can actually be invoked. Previosly, if `foo` was
the name of an automatically-loaded function file but did not actually
define a function `foo`, and there was no execuable `foo`, then `type -q
foo` would lie and say `foo` can be invoked when it can't.
Update tests for new `type` behavior

One of the tests was using `>/dev/null` to suppress the `type` output.
That needs to be `^/dev/null` now, but instead just go ahead and use the
new `-q` flag.
command: Rename -p/--path flag to -s/--search