给定一个URI，返回该URI的基路径。
Parameters:
uri
(String)
URI。
includeQuery
(Boolean)
(default false)
是否包含来自URI的查询字符串和片段
Example
// basePath will be "/Gallery/";
var basePath = bmgl.getBaseUri('/Gallery/simple.czml?value=true&example=false');
// basePath will be "/Gallery/?value=true&example=false";
var basePath = bmgl.getBaseUri('/Gallery/simple.czml?value=true&example=false', true);