enhancements scope transformimpl

This is to answer the question: How to solve the scoping problem using a simple transform? (This might not be the proper solution, just investigating. I know too little about why the current variable scoping is broken.)

What one does: Transform every variable assignment, and reference, but the last one, to a temporary. I.e:

#!python
import math

f = 3
f = 34 + math.sin(f)

class f:
    x = f
    x = 2*f

x = f()

def f(y):
   return x(y)

def x(z):
    return 4

del x

By a single pass (keeping track of names assigned to in AssignmentNodes and references to them in NameNode in a dict) one can without much pain (= ~50 lines of "interesting but not really challenging code") transform this to (where each tmpx variable is a TempNode that doesn't name-clash with variables named tmpx, of course):

#!python

tmp1 = 3
tmp2 = 34 + math.sin(tmp1)

class tmp3:
    tmp4 = tmp2
    x = tmp4

tmp5 = tmp3()

def f(y):
    return x(y) # Python semantics is to keep x=tmp6 here now, and not replace with tmp4? Transform can work either way

def tmp6(z):
    return 4

# since x is deleted, never assign to it in the first place

This will in turn cause static linking in the correct way everywhere.

In addition, some fudging of the function names stored etc. is needed (add an "should_appear_as" attribute to TempNode and use it in code generation of a function), but that appears to be it?

The same transform could easily raise an error when a global name is used before it is defined too.