Rename dec/inc_weak_task_count to inc/dec_live_count and remove register_task/unregister_task. Closes #4768
Add debug info tests
fix typos in sample code, add enum to json encoder, add test case
json bugfixes
tidy
json bugfix
json add enum encoder test case
re-special-case Option in JSON encoding
json tidy
core: Remove GenericChan/Port from prelude. Closes #4762
added issue for reference in FIXME
make Option's iter method use a lifetime
mk: Typo
mk: Run debuginfo tests by default, but only if gdb is available
libcore: LinearMap doesn't need to pass around the bucket vec
core: rename hashmap test functions
core: add LinearMap::find_or_insert{,_with}

This allows for inserting a new value into the map only if it doesn't
already exist in the map.
Add NumCast trait for generic numeric type casts
treemap: use an &mut parameter for skew and split

results in a small performance improvement and reduces the compiled
code size
treemap: avoid swap_unwrap in insert

Performance before:

    std::treemap::TreeMap
                   sequential_ints 0.151877 s
                       random_ints 0.160926 s
                       delete_ints 0.08694 s
                sequential_strings 0.316458 s
                    random_strings 0.290778 s
                    delete_strings 0.169892 s

Performance after:

    std::treemap::TreeMap
                   sequential_ints 0.083971 s
                       random_ints 0.095861 s
                       delete_ints 0.083931 s
                sequential_strings 0.278272 s
                    random_strings 0.240286 s
                    delete_strings 0.173581 s