KT-3192 Drop kotlin.nullable package
#KT-3192 Fixed
Merge remote-tracking branch 'origin/master'
Fixed error on running kotlin-maven-plugin tests
Extract PropertyDescriptor interface
@NotNull for parameter of substitute()
Build jar for j2kConverter
Fix assertions generation for substituted members
Create 'refreshPath' utility function in LocalFileSystemUtils class.
Adding 'Add open modifier to supertype' fix for FINAL_SUPERTYPE error.
Not including empty testcases in suite.

That was sometimes resulting with IDE displaying incorrect number of tests in single run.
Added quickfix for USELESS_SIMPLE_IMPORT.
Added quickfix for REDUNDANT_NULLABLE.
"--kotlinHome" command-line option
Better debugging of arguments in Maven
KDoc tests fixed by setting kotlinHome explicitly
Extract interface: PropertyAccessorDescriptor
Extract interface: PropertyGetterDescriptor
Extract interface: PropertySetterDescriptor
Optimize super-interfaces
QuickFix for PARAMETER_NAME_CHANGED_ON_OVERRIDE.

It renames method parameter to match the name from the overriden method.