Squashed 'site_scons/' changes from 58df9bc..89f0bb7

89f0bb7 Simplify timer and make it compatible with Darwin

git-subtree-dir: site_scons
git-subtree-split: 89f0bb78b8fe2425e38dfd1abff3fb587bb0a55a
Merge commit 'a49979d51121006fa5205ff75275056577d8322c'