Add text-decoration-{color/style/thickness/offset}

[ben-rogerson]

This PR adds a bunch of classes for text decoration including:

tw`box-decoration-clone`
tw`box-decoration-slice`

tw`decoration-solid`
tw`decoration-double`
tw`decoration-dotted`
tw`decoration-dashed`
tw`decoration-wavy`

tw`decoration-auto`
tw`decoration-from-font`
tw`decoration-0`
tw`decoration-1`
tw`decoration-2`
tw`decoration-4`
tw`decoration-8`

tw`underline-offset-auto`
tw`underline-offset-0`
tw`underline-offset-1`
tw`underline-offset-2`
tw`underline-offset-4`
tw`underline-offset-8`

tw`decoration-inherit`
tw`decoration-current`
tw`decoration-transparent`
tw`decoration-black`
tw`decoration-white`
tw`decoration-slate-50`
tw`decoration-slate-100`
tw`decoration-slate-200`
tw`decoration-slate-300`
tw`decoration-slate-400`
tw`decoration-slate-500`
// ...and the rest of the colorset

tailwindcss refs 1, 2