update latest dependency

update latest dependency

	github.com/PuerkitoBio/goquery v1.8.1
	github.com/mattn/godown v0.0.1
	github.com/microcosm-cc/bluemonday v1.0.26
	github.com/spf13/cast v1.5.1

v0.1.5

fix docs

v0.1.4

add sync.Map for thread safety

v0.1.3

add size() function

v0.1.2

Update Built-in functions:

1. remove selection function prefix "node".
2. add absHref/first/last/parents/prarentsUntil functions.

v0.1.1

support nested functions

v0.1.0

1. rewrite core parser
2. add example and godoc

v0.0.9

change tager to private

v0.0.8

fix bultin function bug

v0.0.7

1.Priority order: struct method -> global
2.Support sub struct call parent function.
3.Change builtin function.