Merge pull request #854 from davidfestal/master

Avoid return duplicates of binary-loaded declarations
fix #846 calling overloaded method with vararg
fix #857, typechecking for invocations of flattened function
oops!
errors now go on correct node
update test for change to language module
tests for #857
Use equals() instead of a reference equality check. This was generating
a bug in the IDE when editing the Anything.ceylon file while having the
language module loaded from binaries in the ceylon model.
Add a check to avoid an NPE
ceylon/ceylon.language#364 bug in type arg inference for fold()
Change the name of the default package to a list with one empty string
(instead of a void list of string). This is needed to be consistent with
the way the Java backend manages it. Consistency between front-end and
backend in this regard is necessary to solve
https://github.com/ceylon/ceylon-ide-eclipse/issues/761