Various fixes thanks to rfc 49

(https://github.com/nikomatsakis/rfcs/blob/master/active/0049-bounds-on-object-and-generic-types.md)
Linter is happy on tests
Fixed param bound for os PT
Merge pull request #165 from farcaller/fix-nightly

Various nightly fallout fixes
First chunk of work on a new scheduler
Added docs to os::sched::task
Scheduler now moves in Systick and StackManager
Moved source following the rebase