Runtime: fix infinite recursion when using 'await' in handlers.

Job should be removed from queue before execution.

* da/sim.py:

  -(DistProcess): '_jobqueue' is now a deque instead of list,
  for efficient appending and popping.

  -(DistProcess._process_jobqueue): pop job from '_jobqueue' before
   calling the handler.
Keyword change: process entry point name changed from 'main' to 'run'.

* da/compiler/parser.py:

  -(KW_PROCESS_ENTRY_POINT, KW_ENTRY_POINT): new constants.

  -(Parser.visit_FunctionDef): use new keyword constants to recognize
   process and program entry points.

* da/compiler/pygen.py: generate internal name for process entry point
  to avoid conflict with the 'run' method name used by the
  multiprocessing library.

* da/sim.py: use generated entry point name.

* examples/*: update to reflect this change.
Bump version to 1.0.0b10.