v4.0.0

• Renames .pa-btn-banner to .pa-banner-btn and moves it from _buttons.scss to _banner.scss to better match convention (closes #23)
• Prepends all _structure.scss styles with missing pa- so we don't accidentally override project styles with the same names (closes #22). These include:
  • display-none
  • inline-block
  • padding-0
  • margin-0
  • flex-container
  • flex-center-container
• All variables in _variables.scss are now prepended with pa- to signify they originate from this library in case they get mixed with other imports
  • $color-red was removed as it wasn't used internally and can be easily recreated where needed
• Replaces references of the deprecated window.pageYOffset and window.pageXOffset calls to window.scrollY and window.scrollX respectively
• Bumps dependencies (closes #25)