Enhancement to split and minor fix:
- [Enable file split to emit just -f files even if done by file size](https://github.com/ccaprani/genmq/commit/9426ce935f809174b6afe654cc9c9cbcc79f50b1)
- [Correct zero based indexing for indexed question compilation](https://github.com/ccaprani/genmq/commit/c91eb408ef0bd201f06d1de2a332fcbaa9a7d89e)