Merge pull request #9 from kody-wen/patch-1

Support newer Altium

Use UTF8 string to generate descriptions

1. add convert log for the ad2kicad tool

Add 3D model binder for the footprint

1. Fix file name pattern

1. fix the s-expression parse bug, when left bracket near symbol

1. modify the output s-expression format

1. add description field

Modify readme

modify code style, no feature changed

1. Calculate boundary box to get the text position in symbol

use rd command instead of del to remove the directory

1. add function to convert AD schlib

use a simple way to generate symbol pin