Striprtf

* Removed url hack thanks to a better regex by [stevengj](https://github.com/stevengj) also thanks to [jonas](https://github.com/joans)

* Parameter "errors" was not used anymore. Is now fixed and a test case was added. Thanks [powo](https://github.com/powo) for reporting.

* Clarified the meaning of the `encoding` parameter. It is used as the encoding if an explicit encoding is missing in the rtf file. As the majority of rtf files is encoded in ANSI, this is now the default.
Fixes [41](https://github.com/joshy/striprtf/issues/41).
Thanks to [plessbd](https://github.com/plessbd) and [stevengj](https://github.com/stevengj)

* Parameter `encoding` is now always encoded to `utf-8` output. This release fixes some of the troubles with encodings.
Thanks to [plessbd](https://github.com/plessbd), [stevengj](https://github.com/stevengj) and [nikita-petrashen](https://github.com/nikita-petrashen)

* Added parameter `encoding` to rtf_to_text which is set to `utf-8` as a default. Thanks to [jnth](https://github.com/jnth)

* Fixes [32](https://github.com/joshy/striprtf/issues/32)
Thanks to [akBeater](https://github.com/akBeater), [amirali1690](https://github.com/amirali1690)