Replace dispatch table with simple if:elif:

Changing to a tuple didn't did not solve the issue that RPython could not find a unique name for those function pointers. Now the traditional approach.
This also allows us to get rid of the exception for the HALT bytecode.

Signed-off-by: Stefan Marr <git@stefan-marr.de>
RPython does not like the access of tuples with variable indexes

- converted tuples to lists

Signed-off-by: Stefan Marr <git@stefan-marr.de>