fix chinese
It seems that we should unescape task name returned in json
prevent re-downloading when downloaded file size is smaller than expected.
refactor download tool so I can add aria2c download completion check later
check .aria2 file
if hash fails, don't delete file. instead, rename it to *.error
move download file to top level, so can you hack it easily.
remove download_tool from function arguments
remove expired tasks correctly when paging
fix paging when task number > 100
It seems that we should unescape the original URL returned in json too...
fix paging when the page number > 8
fix bt task
fix #267, paging error for empty task list
fix #268: lx export-download-urls
add --all options to `lx export-aria2` and `lx download-aria2`
check args before login
增加lixian-portal的链接

lixian-portal是我对此cli工具做的一个webui包装（只包装了俺所需的特定场景需要的功能）

它仅仅能完成

* 把bt或者其他类型任务添加到迅雷离线下载
* 等迅雷离线下载完后自动取回
* 取回完后自动删除任务

希望能服务到大家
Merge pull request #282 from layerssss/patch-1

增加lixian-portal的链接
upgrade response check