Multiway join rules

Add rules to compile query to a plan using HyperCube shuffle and multiway join. 
* [x]  add rule to merge left deep join into nary join in logical plan
* [x]  add rule break nary join to hypercube shuffle and local multiway join
* [x]  add rule to instantiate local multiway join (currently we only have leapfrog, but there could be more, so this part is seperated from break break nary join)
* [x]  add rule to place sort before LeapFrogJoin.
* [x]  add unit test
* [x]  add query test
 

I think the Python function `all` can help you here. Something like:

```python
def eval_cond(cond)):
    return all(attr.evaluate(tpl, op.scheme) for attr in cond)

return all(eval_cond(cond) for cond in op.conditions)
```