add __compile helper

ts/index.ts

@@ -1,7 +1,8 @@
 import * as plugins from './smarthbs.plugins'
 export type TTemplateStringType = 'filePath' | 'code'
 
+export let handlebars = plugins.handlebars
 export * from './smarthbs.compile'
-export * from './smarthbs.helpers'
+import './smarthbs.helpers'
 export * from './smarthbs.partials'
 export * from './smarthbs.template'

ts/smarthbs.helpers.ts

@@ -1,4 +1,7 @@
 import * as plugins from './smarthbs.plugins'
 
-export let registerHelper = plugins.handlebars.registerHelper
+plugins.handlebars.registerHelper('__compile', (evaluationString, evaluationContext) => {
+  let template = plugins.handlebars.compile(evaluationString)
+  return template(evaluationContext)
+})