delete the local variable of `parse`

Prevent the use of local variables could not be performed using the external expansion of derivative.
add secondary development interface functions: `onIncludeTpl` and `onParseMethod`

1. onIncludeTpl: Use it when `parse` meet `include`
2. onParseMethod: Expand methods by using the string between "<%" and "%>"
add `options` param for `onIncludeTpl` and `onParseMethod` methods
`onIncludeTpl` and `onParseMethod` can defined in `options`