feat: pass entire theme to css fn

Previously, only tokens were passed to functions passed to css(), but
this meant that breakpoints weren't accessible. Might as well pass the
entire theme object, just in case it's helpful.

index.js

@@ -127,7 +127,7 @@ function hypostyle (theme = {}, config = {}) {
 
   return {
     css (props) {
-      const p = typeof props === 'function' ? props(t.tokens) : props
+      const p = typeof props === 'function' ? props(t) : props
       return Object.keys(p).length ? nano.rule(style(p, t)) : ''
     },
     injectGlobal (props) {

test/hypostyle.js

@@ -272,7 +272,7 @@ export default (test, assert) => {
   test('css as a function', () => {
     const { css, flush } = hypostyle(defaults)
 
-    css(tokens => ({ fs: tokens.fontSize[1] }))
+    css(theme => ({ fs: theme.tokens.fontSize[1] }))
 
     const sheet = flush()