pointerArithmetic now returns UnionExp
Merge pull request #4161 from WalterBright/pointerarith

CTFE: pointerArithmetic now returns UnionExp
pointerDifference() now returns UnionExp
Merge pull request #4162 from WalterBright/pointerdiff

CTFE: pointerDifference() now returns UnionExp
[Refactoring] fix code style in compilable/interpret3.d
[Refactoring] Add exceptionOrCant to make error handling shorter
Merge pull request #4163 from 9rnsr/refactor_ctfe

[Refactoring] A little code cleanup in CTFE interpreter
[nitpick] improve code style
remove ctfeNeedLvalurRef (fin)
+fix for core.demangle unittest
fix for test/fail_compilation/diag11756.d
Tweak error message for test/fail_compilation/fail40.d
fix for test/runnable/opover2.d
ThisExp ref support1
ThisExp ref support2 (AddrExp &this)
Fix for test6178d() in test/runnable/testaa.d
Fix Appender CTFE for the unittests in std.string
Fix test/runnable/testaa3.d
(improve1)
(improve2)