(core) removed getIndexedName from Var.
Replaced with IrUtil#getNameSSA method.
Added SSAVariableRenamer that should be called before code generation:
this transformation sets up the name of local variables, so it is no
longer necessary in backends to use 'indexedName' for local variables.
(backends) added SSAVariableRenamer transform before code generation.
Replaced all uses of 'indexedName' with 'name' in Xtend generators.