Nuclei Missing Critical Options / Default Setting changes needed

[liquidsec]

When conducting very large scans Nuclei will often hang for an extremely excessive amount of time. This situation occurs most commonly in an internal network scenario. This is a combination of two factors:

1. The batch size is much too small. 500 might be a reasonable size, or at minimum 200.
2. The retry is set to 1 by default. Waiting for retries for failed connections can be extremely slow when thousands of requests fail for whatever reason

The retry setting should be an option, and probably the batch size as well, by the batch size needs to be bigger by default.

Consider adding more options, especially those which have to do with optimizations.

[liquidsec]

this was addressed with #799