Add a replace method to an expression

[pombredanne]

This should have the same semantics as the stdlib string.replace():

string.replace(s, old, new[, maxreplace])

    Return a copy of string s with all occurrences of substring old replaced by new. 
    If the optional argument maxreplace is given, the first maxreplace occurrences are replaced.

This is more or less what subs() does but subs is too complex for my case and I do not need recursivity.

I need a simpler lower level way to do only one replacement at a time and not many. There are a few wrinkles in the subs code too where iterating on items() could be replaced by a cleaner and more efficient get() that could be cleaned up too.

[pombredanne]

@Kronuz ping. I recalled this was an area of some interest to you

[pombredanne]

This is supported out of the box with subs(). I am closing.