Add 'inner' keyword

Support for the keyword in PSI and stubs

 #KT-1174 In Progress
Add ClassDescriptor.isInner()

Implement in resolve & lazy resolve; place a stub in resolve-java

 #KT-1174 In Progress
Inaccessible outer class member is now an error

 #KT-1174 In Progress
Labeled this & super to nested class' outer is an error

 #KT-1174 In Progress
Forbid usage of outer's generic parameter in nested class

 #KT-1174 In Progress
Check all modifiers for objects

DeclarationsChecker didn't check visibility modifiers for objects
Report ILLEGAL_MODIFIER on inappropriate 'inner' keyword usage

 #KT-1174 In Progress
Disallow nested classes within inner & local classes

 #KT-1174 In Progress
DescriptorRendererImpl now writes 'inner' for inner classes

 #KT-1174 In Progress
Remove unused method
Remove 'inner enum' hack & fix Java inner class resolve

Inner enum was placed into the class object of the outer class. Remove the
hack from frontend, frontend.java & backend. Fix tests

 #KT-1174 In Progress
Get rid of MutableClassDescriptorLite.isStatic()

isStatic() is now precisely !isInner()
Support inner/nested classes in JVM back-end

 #KT-1174 In Progress
Fix completion for nested class qualified expressions

 #KT-1174 In Progress
ExpressionTypingServices now has QualifiedExpressionResolver

Re-generate injectors.
Add TemporaryBindingTrace.getOwnDiagnostics()

To get a collection of only those diagnostics which were added in a particular
temporary trace
QualifiedExpressionResolver imports from objects on demand
Add factory method to ChainedScope
(TODO) Resolve qualified expressions in type checker

BasicExpressionTypingVisitor now tries to use QualifiedExpressionResolver to
resolve every dot qualified expression consisting of simple name expressions.
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