let's just commit these first

- use 0 instead of 0px
- use solid color in some places instead of rgba
- added variable $expando-button-style. if set to `old` will use the
  previous circle button. any other value will make it use small button
  style
- added variable $vendor-prefixes to control whether vendor prefixes in
  some mixins will be included or not
- break RES' comment nav buttons at the eighth button instead of ninth
- shitty first attempt at "fixing" contest infobar
- darken RES' my subreddits dropdown
style for delete multi

also apply default button style to cancel button when editing/replying
comment