Soupsieve

- **FIX**: When giving a tag to `select`, it should only return the children of that tag, never the tag itself.
- **FIX**: For informational purposes, raise a `NotImplementedError` when an unsupported pseudo class is used.

- **NEW**: Official 1.0.0 release.

- **NEW**: Drop document flags. Document type can be detected from the Beautiful Soup object directly.
- **FIX**: CSS selectors should be evaluated with CSS whitespace rules.
- **FIX**: Processing instructions, CDATA, and declarations should all be ignored in `:contains` and child considerations for `:empty`.
- **FIX**: In Beautiful Soup, the document itself is the first tag. Do not match the "document" tag by returning false for any tag that doesn't have a parent.

- **NEW**: Add support for non-standard `:contains()` selector.
- **FIX**: Compare pseudo class names case insensitively when matching unexpected cases.
- **FIX**: Don't allow attribute case flags when no attribute value is defined.

- **NEW**: `mode` attribute is now called `flags` to allow for other options in the future.
- **FIX**: More corner cases for `nth` selectors.

- **FIX**: Previously, all pseudo classes' selector lists were evaluated as one big group, but now each pseudo classes' selector lists are evaluated separately.
- **FIX**: CSS selector tokens are not case sensitive.