Htmldoom

- Minor bug fix: yaml import error.

- Added support for defining HTML components using YAML syntax.
- Added `loadtxt` and `loadraw` in the `util` module to support loading elements directly from given file path (like `loadyaml`)
- Added optional `static` argument in the file loaders as a switch to decide whether to escape all the `{` and `}` with `{{` and `}}` respectively. Default is `False`.
- Some docs improvement.

- Fixed docstrings and * import in `htmldoom.url` module.

- Added 3 url helpers: `htmldoom.url.url`, `htmldoom.url.http`, `htmldoom.url.https`

* Some minor fixes.
* Documentation and test cases updated.

* Added a fast dynamic elements rendering mechanism.