Don't require the stack module to find the last value cache
Refactor stopwatch class
Correct Statistic prototype
Make LastValueCache take a /const/ array of stat names
Stats bug fixes
Cope with a statistic being passed a NULL LVC (useful in UTs)
Add comment about allowing NULL LVcs
Remove pjsip include from lvc
Make load monitor methods virtual to allow for mocking
Move interposers to cpp-common
Merge remote-tracking branch 'remotes/origin/stats_refactor' into repeat_for