组件拖动新建，限制层和组件的拖放范围和步调
解决冲突
拖动新建自动加入层
Merge branch 'jack' of https://github.com/lln7777/zhuyun into jack

Conflicts:
	public/javascripts/funcs.coffee
coffee->js
优化拖动检测
画线
完善拖动的碰撞检测
画折线
编写线条抽象类
fix line
Merge branch 'ansel' of https://github.com/lln7777/zhuyun into sx

Conflicts:
	public/javascripts/lines.js
fix bug
Merge branch 'ansel' of https://github.com/lln7777/zhuyun into sx
测试折线
test
完善画布操作
层模块化
修改Line类，fix bug
Merge branch 'jack' of https://github.com/lln7777/zhuyun into jack

Conflicts:
	public/javascripts/funcs.coffee
	public/javascripts/funcs.js
	public/javascripts/global.coffee
	public/javascripts/global.js
	public/javascripts/index.js
	views/index.ejs