Pause/Resume BasicThread's doUpdate calls.

This feature is useful for debugging and giving time for people to move the camera around before an event occurs for example...
API pause/resume/isPaused. isRunning() -> true if thread running and not paused

+ update the unit test
Rename Pause/Resume by setIdle/isIdle, isRunning relies only on m_isRunning
Merge branch 'master' of git.assembla.com:OpenSurgSim into feature/pauseResumeThread
Merge branch 'feature/IdleThread' into 'master'

Idle thread

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1020234