flag to specify which line type setings to use

[diabolusss]

Hello!
Great tool, thank you for your job.
Posting just in case someday it will be useful.

While WEB version always uses multiple threads, cli version based on autodetected line type may limit concurrency which may affect results as can be seen in screenshots below.

Some flag, i.e. --line-type --concurrency or similar, will be useful to override such cases.
speedtest++ 10:19
Speedtest Web 10:20
speedtest++ 10:36
Speedtest Web 10:37