add new vars for common border-radius, upping border-radius of inputs to 4px; add border-radius changes to -large, -small, -mini for buttons and paginations

add new vars for common font-sizes and paddings with large, small, and mini components; resize pagination and buttons to better match each other

change up box-shadow mixin usage everywhere to use escaping again, or local var if necessary for further var evaluation

fixes #4445: .btn-link shouldn't have a pressed button-like state at all, so nuking everything on :active as well

update button styles to use updated 14px base font size, align carets to others with no opacity changes

remove @shadow instances and replace with escaped values, update mixins to not use a default value at all

1. Removed borders on .btn and increased line-height 2px to compensate
2. Set buttons to use the endColor of the gradient as the background-color by default for extra contrast between button and background
3. Set a 5% darker background-color on hover of buttons just for IE7

fix other instances of mixins, swap use of box-shadow everywhere, include border-radius and transition

removing duplicate reset filter since we changed the main button to use buttonBackground mixin, per #2024

Clean up inverse button using variables, adding button group examples. Also adding inverse inline label