Fix generation of core.BNLog

Most of the BNLog API methods are just variable length arguments of strings. BNLog also includes a `level` parameter, which causes a `TypeError` when `binaryninja.log.log(level, msg)` is called, because it is expecting all parameters to be strings. This PR fixes it so that `BNLog` is correctly generated.

Note: I haven't actually tested this to verify `generator` still works, because my Makefile is messed up currently.