* These have a different reference count to consider for extending
the value, pass this as an argument.
* This also splits unary and binary operation code generation which
is overdue too.
* Avoids assigning back to module dict if the value didn't change.
* More work is needed for this to be actually effective for all
helper kinds, and esp. for Python3 unicode.
* For some in-place operations, support for writing module variables
has been added, including avoiding unnecessary write backs.
* For Python2, in-place operations for integers got special cases, like
they are for CPython. This preserves the Nuitka speedup.
* For strings that are not used elsewhere, the string is expanded in the
old storage location, which makes things much faster for large strings.
* Currently only local variables are handled this way. More kinds of
storage, global variables, attributes, etc. are to follow.
* This fixes part of Issue#124.
