Turmit stack size was 0 sometimes
Mutator sometimes delete leading to empty expressions

Now steps count evolve given the try number from 100% to 33%

first turmit that looks nice :D

A world (World) is a place where turmit can run (LivingTurmit) and has
methods to determine its fractam dimention and to save a representing image

L'essentiel du main sera déplacé dans un module

Bugfixes in Turmit tests and in rpn op wrapper (in argument orders)

Add small test for Turmit.__call__()

Adding prog attribute to Turmit (storing a RpnExpr)

Moving RPN stuff in dedicated module

dup, and, sub, lshift