SI-7445 ListMap.tail is returning wrong result

Reverted the commit that introduced the bug, and modified HashMap to no
longer assume that tail is O(1).

Review by @Ichoran, @soc
Add support for Java 8 in our build.

We explicitly check for supported Java versions in our build.
Add Java 8 to the list of supported versions.
Work-around for partest failure due to JDK bug.

JDK7 and JDK8 have a bug that causes JVM to print some warning about
applets that is unrelated to whatever we are testing in Scala. Let's
work it around using test/files/filters mechanism that allows us to filter
out output lines based on regexp.
Make abstract-report2 test less dependent on std library.

Replace the use of `Ordering` by custom, dummy trait Xyz defined in test's
source.

By not inheriting from Ordering in abstract-report2 we make the test
less dependent on both Scala and Java library. The reason we are less
dependent on Java is because Ordering extends Java's comparator.

This change is motivated by the fact that Java 8 introduced default
method `reversed` to Comparator interface and we get a failure due to
conflicting inheritance:

-abstract-report2.scala:9: error: trait Bippy inherits conflicting members:
-  method reversed in trait TraversableOnce of type => List[(T2, String)]  and
-  method reversed in trait Comparator of type ()java.util.Comparator[T3]
-(Note: this can be resolved by declaring an override in trait Bippy.)
-trait Bippy[T1, T2, T3] extends Collection[T1] with TraversableOnce[(T2, String)] with Ordering[T3]
-      ^
Add cross suffix customizability for modules

For each module whose version can be specified using
the property "xxx.version.number", it is now possible
to specify its cross version suffix by using an
optional property "xxx.cross.suffix".

If such a property is not defined, then continue to
use the string "_${scala.binary.version}", as before.
fix to partest.cross
Expose seq field for variable arity definitions

In 2.11 we've changed TupleClass, ProductClass and FunctionClass
endpoints to be exposed as (Int => Symbol) functions that never throw
exceptions but rather return NoSymbol instead of previous error-prone
indexed access on array that could explode.

While simplifying one use case (indexed access) it complicated
ability to check if symbol at hand is in fact a tuple, product or
function:

  (1 to 22).map(TupleClass).toList.contains(symbol)

To cover this extra use case we add a seq method to the variable arity
class definitions that exposes a corresponding sequence of class symbols:

  TupleClass.seq.contains(symbol)
Merge pull request #3398 from densh/topic/var-arity-class-seq

Expose seq field for variable arity definitions
an optimization for c.eval

People are very frequently using c.eval in order to obtain underlying
values of literals. Spinning up a new compiler for that modest purpose
is a gross waste of fossil fuels.
Merge pull request #3399 from xeno-by/topic/eval

an optimization for c.eval
SI-6879 improves Context.freshName

Instead of per-compilation unit unique counters, the freshName API now
uses a per-Global counter. Fresh names now also contain dollars to exclude
clashes with supported user-defined names (the ones without dollar signs).

This doesn’t fix the bug, because per-Global counters get created anew
every time a new Global is instantiated, and that provides some potential
for name clashes even for def macros, but at least it completely excludes
clashes in typical situations.
addresses pull request feedback
Merge pull request #3401 from xeno-by/topic/fresh

SI-6879 improves Context.freshName
Versions of modules part of Scala 2.11.0-M8.
Merge pull request #3394 from cunei/wip-cross-suffix

Add cross suffix customizability for modules
Merge pull request #3404 from gkossakowski/java8-support

Preliminary support for building and testing with Java 8
Merge pull request #3388 from rklaehn/issue/7445

 ListMap.tail is returning wrong result
Merge pull request #3390 from adriaanm/release-2.11.0-M8

Versions of modules part of Scala 2.11.0-M8.
SI-5722 Macrofy classOf[T]
WIP.