Modify direct dynamic model computation

Refactor in order to unify the DDyM computation for floating base and
fixed base robots into the same function `floating_direct_dynmodel()` in
`nealgos`.
Rename function

Rename `floating_direct_dynmodel()` to `direct_dynmodel()` in `nealgos`.
Update function calls in `Robot` class
Remove not needed code in `pysymoro/dynamics.py`
Remove unused code in `pysymoro/tests/oldtest.py`
Rename `pysymoro/dynamics.py` to `pysymoro/baseparams.py`

Rename `pysymoro/dynamics.py` to `pysymoro/baseparams.py`.
Update module import calls accordingly.
Rename function name in `pysymoro/baseparams.py` and update accordingly.