Parse icons with two names for same icon in css
Use font size of 87.25% so no icons will be clipped

No clipping occurs for size >= 16
Tested with Font Awesome 4.0.3
Should clipping occur with another FA version or size a message will be printed
Infix argument to put extra string after filename and before .png extension

Use this for example to generate names like: icon-name-30px.png and icon-name-2x.png