Fix/#55 #56 modules

[odersky]

Fixes for problems related to modules.

[odersky]

Review by @DarkDimius, @sjrd

[DarkDimius]

Unfortunately #56 isn't fixed yet.
While trying to create object A{} after class A{} in such code
class D {def p = {class A{}; 1}}
I've got an assertion failure

[error]     at scala.Predef$.assert(Predef.scala:155)
[error]     at dotty.tools.dotc.core.Types$CachedTermRef.<init>(Types.scala:1186)
[error]     at dotty.tools.dotc.core.Uniques$NamedTypeUniques.newType$1(Uniques.scala:59)
[error]     at dotty.tools.dotc.core.Uniques$NamedTypeUniques.enterIfNew(Uniques.scala:63)
[error]     at dotty.tools.dotc.core.Types$TermRef$.apply(Types.scala:1211)
[error]     at dotty.tools.dotc.core.Symbols$$anonfun$newCompleteModuleSymbol$1.apply(Symbols.scala:160)
[error]     at dotty.tools.dotc.core.Symbols$$anonfun$newCompleteModuleSymbol$1.apply(Symbols.scala:159)
[error]     at dotty.tools.dotc.core.Symbols$class.newModuleSymbol(Symbols.scala:132)
[error]     at dotty.tools.dotc.core.Contexts$Context.newModuleSymbol(Contexts.scala:50)
[error]     at dotty.tools.dotc.core.Symbols$class.newCompleteModuleSymbol(Symbols.scala:157)
[error]     at dotty.tools.dotc.core.Contexts$Context.newCompleteModuleSymbol(Contexts.scala:50)
[error]     at dotty.tools.dotc.transform.PostTyperTransformers$PostTyperTransformer.reorder0$1(PostTyperTransformers.scala:57)

[DarkDimius]

to experience that failure you can run
testOnly test.transform.PostTyperTransformerTest
on this branch
https://github.com/DarkDimius/dotty/tree/issue56

[DarkDimius]

Works for me.
LGTM, but better to squash commits before merging.

[DarkDimius]

@odersky, thanks for fixing this quickly.

[odersky]

@DarkDimius can you squash the commits and merge? I am overwhelmed with other stuff.

[DarkDimius]

No problem, I'll do it.
I'll create a pull request for PostTyperTranformer, including those your fixes as a separate commit.

[odersky]

OK, sounds good

[DarkDimius]

merged as part of #64