- clerical updates

- minor update to gcc instructions

- comments in StackFrame.h

- clerical update

- tighten up one assertion
- add ReadyQueue::probe() for non-atomic check before stealing

- bug in Fred::migrate()
- clerical updates

- move IdleSpin into idle loop

- minor cleanup fix in stats
- clerical update in EventScope

  . switch default setting to using background poller
- also reduce maximum number of poll events to reduce bursty behaviour
-> parameters (256) should probably be adjusted based on core/fibre count?

- epoll/stats update
- clerical updates

- add nanosleep to interface

- fix fibre-specific destructors