rules api refactoring

- split rules to 2 types: node checker, and tag checker
- filter rules by tags in iterator
- filter rules by scope (now it's only function scope)
- patch rule files (set scope everywhere)
reworking jsdoc-helpers, introducing jsdoctypeparser

- remove doctrine, add jsdoctypeparser for parsing doc types
- rename jsDoc to jsdoc for simplicity
- rename forEachTag to iterate
- remove data property, extend DocComment object
- simplify param checkers

Fixes #3