fix single select title functionality. improve speed
fix single select title functionality. improve speed

Don't select the blank title option of the select if there is already an
option that has the "selected" attribute. Previously, if a single select
had a title, it would override the option with the "selected" attribute
and select the blank title option.

Also, slight improvement in rendering speed for selects with a lot of
options by using native JS.

silviomoreto/bootstrap-select,TeleginS/bootstrap-select,anhtranqs3/bootstrap4-select,wearespindle/select3,tommydevdocs/bootstrap-select,jesenko/bootstrap-select,jesenko/bootstrap-select,emilmoe/bootstrap-select,Burick/bootstrap-select,zhaoyan158567/bootstrap-select,TeleginS/bootstrap-select,nhahv/bootstrap-select,tommydevdocs/bootstrap-select,nhahv/bootstrap-select,silviomoreto/bootstrap-select,QthCN/bootstrap-select,performancematters/bootstrap-select,emilmoe/bootstrap-select,coopsource/bootstrap-select,zhaoyan158567/bootstrap-select,think2011/bootstrap-select,JoachimZ/bootstrap-select,chengky/bootstrap-select,bookbrainz/bootstrap-select,iaesaudi/bootstrap-select,Burick/bootstrap-select,nayosx/bootstrap-select,nayosx/bootstrap-select,bookbrainz/bootstrap-select,anhtranqs3/bootstrap4-select,wearespindle/select3,coopsource/bootstrap-select,iaesaudi/bootstrap-select,QthCN/bootstrap-select,chengky/bootstrap-select,think2011/bootstrap-select,JoachimZ/bootstrap-select,performancematters/bootstrap-select