ENH: improve controls for Time (issue #910)

- relocate some standard functionality to TimePaths to allow a lighter
  means of managing time directories without using the entire Time
  mechanism.

- optional enableLibs for Time construction (default is on)
  and a corresponding argList::noLibs() and "-no-libs" option

STYLE:

- mark Time::outputTime() as deprecated MAY-2016

- use pre-increment for runTime, although there is no difference in
  behaviour or performance.

applications/test/parallelOverset/write.H

@@ -1,4 +1,4 @@
-    if (runTime.outputTime())
+    if (runTime.writeTime())
     {
         volVectorField gradT(fvc::grad(T));