Zimscraperlib

* replaced BeautifoulSoup parser in rewriting (`html.parser` –> `lxml`)

* detect mimetypes from filenames for all text files
* fixed non-filename based StaticArticle
* enable rewriting of links in poster attribute of audio element
* added find_language_in() and find_language_in_file() to get language from HTML content and HTML file respectively
* add a mime mapping to deal with inconsistencies in mimetypes detected by magic on different platforms
* convert_image signature changed:
* `target_format` positional argument removed. Replaced with optionnal `fmt` key of keyword arguments.
* `colorspace` optionnal positional argument removed. Replaced with optionnal `colorspace` key of keyword arguments.
* prevent rewriting of links with special schemes `mailto`, 'tel', etc. in HTML links rewriting
* replaced `imaging` module with exploded `image` module (`convertion`, `probing`, `transformation`)
* changed `create_favicon()` param names (`source_image` -> `src`, `dest_ico` -> `dst`)
* changed `save_image()` param names (`image` -> `src`)
* changed `get_colors()` param names (`image_path` -> `src`)
* changed `resize_image()` param names (`fpath` -> `src`)

* fixed URL rewriting when running from /
* added support for link rewriting in `<object>` element
* prevent from raising error if element doesn't have the attribute with url
* use non greedy match for CSS URL links (shortest string matching `url()` format)
* fix namespace of target only if link doesn't have a netloc

* added UTF8 to constants
* added mime_type discovery via magic (filesystem)
* Added types: mime types guessing from file names
* Revamped zim API
* Removed ZimInfo which role was tu hold metadata for zimwriterfs call
* Removed calling zimwriterfs binary but kept function name
* Added zim.filesystem: zimwriterfs-like creation from a build folder
* Added zim.creator: create files by manually adding each article
* Added zim.rewriting: tools to rewrite links/urls in HTML/CSS
* add timeout and retries to save_file() and make it return headers

* fixed `convert_image()` which tried to use a closed file

* exposed reencode, Config and get_media_info in zimscraperlib.video
* added save_image() and convert_image() in zimscraperlib.imaging
* added support for upscaling in resize_image() via allow_upscaling
* resize_image() now supports params given by user and preservs image colorspace
* fixed tests for zimscraperlib.imaging