fix error code
trim down some errors relating to incomplete control structures
Allow using the ModuleVisitor without side effects (only reusing the
existing modules and packages)
This is for the IDE (EditorPhasedUnits and binary-archive
ExternalPhasedUnits typechecked on-the-fly)
This doesn't change anything by default
ExpressionVisitor: fixed NPE
Bottom -> Nothing

See #186.
Void -> Anything

See #186.
Merge pull request #948 from lucaswerkmeister/master

4× Bottom → Nothing
attempt to solve #950
add error code for IDE
Fix #944
Add Throwable and Error.
Don't exclude static references from having their types checked (fixes ceylon/ceylon-compiler#1580)
Don't break encapsulation by letting outsiders change the internals of the Module
squash npe
minor fix to error message
Issue #915: resource expressions that are instantiations must be Destroyable; otherwise resource expressions must be Obtainable.
Issue #915: Move the test for whether an expression is an invocation and make it public so that it can be used by the backends.
Add j.l.Error and j.l.Exception to the set of non-importable types (see ceylon/ceylon-compiler#1586).
SpecificationVisitor: allow metamodel access even to uninitialised values
Declaration: add qualifier for local types

So two local types of the same name but different scope are not equal