1.2.1

fix imports on browser
improve error reporting on browser
fix Runtime error reports from imported files
fix 'File not found' import error reporting

1.2.0

- mixin guards
- new function `percentage`
- new `color` function to parse hex color strings
- new type-checking stylesheet functions
- fix Rhino support
- fix bug in string arguments to mixin call
- fix error reporting when index is 0
- fix browser support in webkit and IE
- fix string interpolation bug when var is empty
- support '!important' after mixin calls
- support vanilla @keyframes directive
- support variables in certain css selectors, like 'nth-child'
- support @media and @import features properly
- improve @import support with media features
- improve error reports from imported files
- improve function call error reporting
- improve error-reporting
