Fix tabs order, avoid appearance of tab header on next row

### Fixing appearance of tab header on next row by rechecking offsets.
Scenario: tab headers are pushed to tabdrop but one of the pushed tabs have `.active` class which updates the title of the `li.tabdrop.active`. That results in undesirable push of the last visible tab header down to next row. This commit fixes that by rechecking offsets. Also incorrect tab order is [fixed](https://github.com/pribilinskiy/bootstrap-tabdrop/commit/04e583be5b93ea710df75cc08250644a6441243e#diff-27f32a73e621d797e5ebd2f408b54862R116).