Attempt #1 to optimize findMember

Keeps fingerprints in scopes which are bitsets telling you what the last 6 bits of each hashcode of the names stored in the scope are. findMember will avoid looking in a scope if inferprints do not match.
Attempt #2 to optimize findMember
Attempt #3 to optimize findMember

Fixed fingerPrinting scheme to work with rehashes, also added finger prints to typedIdent searches.
Attempt #4 to optimize findMember

broke out findMembers as a separate operation to streamline the code. findMember itself still needs to be optimized.
Attempt #5 to optimize findMember.

Specific optimizations to findMember that have become possible because findMembers is its own function now.
Attemmpt #6 to optimize findMember

Replace scope by ::-list, where new elements are added at the end.
Fixing problem that caused fingerprints to fail in reflection.
Also fixed test case that failed when moving to findMembers. Avoids similar problems in the future by renaming nme.ANYNAME
Attempty #7 to optimize findMember

memberType operations are not cached, so that at most one memberType is taken per found symbol.
Attempt #8 to opimize findMember.

Only consider DEFERRED members in 2nd pass.
Attempt #9 to opimize findMember.

Also avoid recomputation of memberType in findMembers
Variation #10 to optimze findMember

Undoing the memberType caching. This seems to make it slower rather than faster. Also, comparing new vs old statistics shows that only very few asSeenFrom operations are saved by the caching.
SI-6086 magic symbols strike back

Some of the symbols inside the compiler get created on the fly,
because there are no physical entities in classfiles corresponding to them.

This curious fact needs to be taken into account when loading symbols,
so that the magic symbols get correctly loaded by reflective mirrors.

magicSymbols (as defined in Definitions.scala) include not only
top-level classes, but some other stuff (e.g. String_+ or methods on Any).
Hence a filtering was done to exclude the stuff that's irrelevant
to reflective symbol loading.

Unfortunately a filter was configured to accept only _.isClass,
which consequently ruled out scala.AnyRef (that is a type alias).
test case closes SI-6047

The bug is not reproducible both in M4 and in M5.
SI-5895 fixes FieldMirrors

reflectField now accepts getters and setters along with the field symbols,
it also checks whether a field has a reasonable binary representation
(this is necessary, because ctor parameters that are unused outside of their
declaring constructors don't get compiled down to Java fields/methods).
Increase partest timeout and emit warning when it hits.
SI-6095, SI-6098 - clean up public API, add deprecations

Remove Scheduler, Cancellable, and Task trait.
Hide impl.Promise object.
Deprecate managedBlock methods in TaskRunners.
Remove duplicate toBoxed method and pointless renaming import.
Remove duplicate import of CanBuildFrom and Builder in Future.
Organize imports in impl.Promise.

Review by @axel22 and @heathermiller
SI-5892 allow implicit views in annotation args

the problem was that lazy annotations got completed in phase pickler.
the `inferView` method in Typers bails out if `isPastTyper`. now the
lazy annotations completes `atPhase(typerPhase)`. test case in `pos`.

the second test case in `neg` is for another bug that is discussed in
a comment of SI-5892. when type checking arguments of type parameter
annotations, the class members should not be in scope. this was alreay
fixed in 9129cfe9.
SI-5695 removes Context.enclosingApplication

Apparently it's impossible to find out the enclosing Apply node
if you're an argument being typechecked (because the arguments
are typechecked separately from the enclosing Apply).

This functionality is by far not a core feature of macros,
so I'm removing it.
SI-6089 better tail position analysis for matches

we mistakenly went into apply nodes to look for matchEnd-labeldefs
in tail positions -- only apply nodes that jump to labels in tailpos
should be traversed (this arises for nested matches)
Fix SI-5937.