======
用于解析简单的字符串为对应的标签树，支持自定义标签
tagList (default: ['b', 'i', 'u']);
要解析的标签列表
brSym (default: 'br');
换行符，设置 null 来忽略；
var parser = btagParser();
parser(str[, translateCharacter]);
translateCharacter用于确定是否将特殊字符转义，默认为false
var str = '<i>To be</i> or <i><b>not</b> to be</i>, That is a <b>question</b>';
var parser = btagParser();
parser(str);
/*
[
{
"type": "i",
"value": [
{
"type": "normal",
"value": "To be"
}
]
},
{
"type": "normal",
"value": " or "
},
{
"type": "i",
"value": [
{
"type": "b",
"value": [
{
"type": "normal",
"value": "not"
}
]
},
{
"type": "normal",
"value": " to be"
}
]
},
{
"type": "normal",
"value": ", That is a "
},
{
"type": "b",
"value": [
{
"type": "normal",
"value": "question"
}
]
}
]
*/