add selectall action
use typeof check first. for the argument may be zero
updateselection添加一个新参数，表示是否全选
update backspace method。remove direct use of selection.selectionObj
update
update log & maxCodeLine
mousedown事件监听的是整个editor的dom
update transEventPos2CuretPos method
update transEventPos2CuretPos method
update transEventPos2CuretPos method: rowIndex must be less than the model's length
mousedown和click绑定在editor的dom上
findTokens，判定是同一个token还需要来考虑startLine和endLine