1.0 dev

Significant changes:
* No more numeric error codes :smirk: 
* Error message now [includes messages of all nested errors](https://github.com/nodules/terror/issues/18#issuecomment-65216459);
* Stack traces became clean and shiny: no more error constructor calls or empty lines in traces!
* `Terror#log()` doesn't timestamp messages now, it's a work of the logger;
* `Terror#log()` output formatting has been changed to `<level> <code> <message>\n<stacktrace>`;
* Bunch of v8 optimization bailouts avoided, especially deoptimization of constructors;
* `objex` has been thrown out for the reason above;
* unit testing framework `nodeunit` was replaced with `mocha` and `chai`
* Argument `name` is required now for `Terror.create()` calls.

C'mon, buddies, lets review it!

\cc @ruslankerimov @Flackus @narqo @an9eldust @isquariel @miripiruni @ZooBestik 
Confusing `copyPlainObject` has been renamed https://github.com/nodules/terror/commit/76220826f598a29d4f8b1d4a8f2751591d0844c4