no more need to lift Cells into Exprs with gRead in right-side expressions
generating labels without a colon after them
added a String field in GOps for commenting operator sequences
Possibility of commenting any operators by putting # <comment string> after them.
HCode monad was changed. Now last generated operator is stored in State part
and so it can be modified after generation (amended with a comment, for example).
When generating next operator previous one got stored in Writer.