Option to make attribute and content check case insensitive

[BTWS2]

The non-emmet way allows for case_insensitve values for attributes e.g.

html.make_item("<meta> has the 'UTF-8' charset attribute",
               el_meta.attribute_exists('charset', "UTF-8", case_insensitive=True))

Is it possible to also support these use cases?

• Case insensitive value with Emmet

html.make_item_from_emmet("<meta> has the 'UTF-8' charset attribute",
                          "meta[charset='UTF-8']",
                           case_insensitive=True)

• Case insensitive content with Emmet

html.make_item_from_emmet("<title> has Hello World as content",
                          "title{Hello World}",
                           case_insensitive=True)

• Can you also add case insensitivity option to has_content()?
• Update docs
• Tests were added