[Feature request] Auto-detect long reads

[linsalrob]

When using long reads (and not fully reading the manual) you may forget to add the --longreads flag. Phables doesn't work well on long reads without that flag, but is excellent on long reads with the flag.

It would be great to either automatically turn on long reads if the reads are long, or at least issue a warning that the reads are long and so I should use the --longreads flag (or that I should go read the manual!)