add tail call elimination to prevent python recursion limit errors, make into a loop

[hornc]

RecursionError: maximum recursion depth exceeded while calling a Python object
on running this code:

ιιθθιθ
ΙΣιυΣΘ
Σ

Should be sufficient to check whether last char in a statement def is the symbol representing that fragment: ΙΣ...ΣΘ where Σ is the tail-called symbol in the example. Then simple loop over Σ, Deadfish overflow checking and fragment breaking must still be in effect...