Add a runAll target to the Python section so as to run all the codes.
Still need pthreads library for the C++11 thread and futures codes.
Switch back to using LDC for the D builds.
Trivial change to the D parallel reduce code to reduce character count and improve readability.
Remove creation of a list via list comprehension in favour if using the generator expression as an iterable. Remove some extraneous thread management. Remove commented out extraneous codes.