Fixes and features for javap (fixing SI-6894)

Output filtering is refactored for javap6.

That means javap6 also supports -raw.

Handling of # is: Foo#foo filter on foo,
Foo# filter on apply, -fun Foo#foo for anonfuns of foo,
-fun Foo# anonfuns filtering on apply.

One is loath to add command options, so it's not possible
to ask for "only apply methods in anonfuns pertaining to
a method."  Hypothetical syntax to say "show me the
apply only": -fun Foo#foo(), for future reference.

This is supplemental to #1849 which I ought to have closed while I was push -f'ing more stuff late nights.

An additional use case is to ask for the App init body:
scala> :javap -app grouped.Test#
  public final java.lang.Object apply();

Review by @paulp