option updates and 4.0 merge

[fklassen]

As per discussion with @synfinatic

I am thinking the following, and please let me know if you have concerns:

1. get rid of --rdtcs and --rdtsc-clicks - as discussed
2. get rid of --sleep-accel - already done. Not required now that timestamps happen after packet is sent, and time stamping doesn’t happen when it detects that TX is falling behind. Now --mbps as fast as or faster than --pps
3. get rid of --sleep-mode - v325 not as good as current version

Questionable:

1. is --enable_file_cache required if we have --preload-pcap ?
2. is --pktlen real? I haven’t seen anything lately that captures bigger than caplen, so can this be removed?
3. Juniper DLT - I notice this in 4.0alpha1. Seems cool, but is there a demand? Has it been tested, i.e. if I copy it over without testing will it work?
4. Other 4.0alpha1 stuff - I find lots of other good things in it (other than cmake) that I would like to copy over