New Intention Action: Replace with operator assign

Replaces a statement of the form a = a + b with a statement of the form
a += b.
New Intention Action: Replace with traditional assign.

This takes an expression of the form a += b and converts it to an
expression form a = a + b.
Merge pull request #386 from pk382/operator-assign-intention

Intention: Convert between "+=" and "a = a + b"
#KT-4563 Fixed
Reuse intention test data in inspection tests
Updated to IDEA 135.667 (13.1.2 EAP)
Switch Optimization
SwitchOptimization: generating `lookupswitch' opcode for 'when' in case of integral types
Switch in when-expression: choice between lookupswitch and table switch (heuristically)
Tests for switchOptimization: shuffled and added sparse version
Refactored tests for switch optimization of When expression
Optimizations of When expression with int constants: pull request review fixes
Optimizations of When expression with int constants: heuristics from openJDK for decision about using tableswitch/lookupswitch
Optimizations of When expression with int constants:
Added test with dense constants (tableswitch should be used)