(models) added TypeGen type
(models) handle ExprTypeConv in ValueUtil
(ir) castToUnsigned always converts to unsigned
(ir) corrected IrTyper for typing of sized ExprInt
(compiler) added transformIndexes method to cast indexes to unsigned
Before the casts were only done for loads, not stores.
(vhdl) removed caseExprInt in cast adder
It's no longer necessary because indexes are always cast to unsigned now