Issue #1325: Add a new kind of test based around tracing the execution of a ceylon program,
and making assertions about the methods and lines that are stepped through.

This is a little tricky because we don't want to add tools.jar to
the classpath, since that breaks the compiler tests (and the compiler). We
leap though this hoop by keeping TracerImpl.java off the source path
and compiling it in DebuggerTest.
Issue #1325: Add AssertFalse.ceylon
Issue #1325: Fix position of assert(false) and assert(anythingelse)
ws
Issue #1325: Fix the position of various synthetic things.