remove a bunch of old task apis. update test_task to new api.
Merge pull request #66 from chipdude/chip/stacks

Much smarter stack cache, with larger defaults.
Merge branch 'master' of github.com:toffaletti/libten
correct iterator usage
go back to count based max for stack cache
register signal stack with valgrind
fix hang on parse_arg, like --help
re-add cache_maxsize
use static_cast minimally, avoid reinterpret_cast where possible
don't do math on void*, it's gcc-specific and warns
use atomic load() and store()
blow away unhelpful stack cache only if it's at least half-full