Mark attributes as boolean in abbreviations

Users can dot after attribute name in expression to mark this attribute as boolean (e.g. name and value are equal). Depending on preferences, the `div[attr.]` expression can be transformed into `<div attr="attr">` or `<div attr>`

Also, `profile.allowCompactBoolean` and `profile.booleanAttributes` were added to add more control and convenience for users.

Closes #160