`AutoFileReload` is useful for almost all occasions where hot-
reloading is needed. Thus it belongs into a separate class for
easier reuse.

Add command line argument to specify a cpuid and cpuset cgroup name for the engine.
The engine tries at startup to move itself to the cpuset provided or set the cpu affinity.
This will allow a wrapper program to free a core for the engine, minimizing latency jitter or CPU starvating.

Add script which will isolate a dedicated CPU for the mixxx engine.

- Select a CPU and its hyperthread partners (last real cpu)
- Create cpuset groups for the system with all other cpus and move all
processes there.
- create a cpuset group for the engine and one for all hyperthreading partners
- try to take hyperthread cpu offline
- start mixx with provided paramenters and cgroup parameters

when mixxx is stopped
- take cpu online again
- move all processes back to the root group
- delete cpuset groups

This catches all additions as before but in a simpler way.
Also catches updates and removals (when the track waveform has been cleared).

…isFeature

…act what's needed

this sets hotcue indices so they are in ascending order