Fixed #8

Moved ``sch_unload_current()`` function call to after the memory deallocation.
Because of rearrangement, ``os_thread_delete(0)`` no longer generates function
call to ``thd_delete_static()``. In ``os_thrad_delete(0)`` current thread will
unload itself after releasing memory.

Merge branch 'master' of github.com:jdoe95/mrtos

added cm0plus platform in README

Fixed README headings display issue