Select2 differences

Project demonstrates behavior differences between select2 version 3.5.3 and version 4.0.x.

• test_353.html using version 3.5.3
• test.html using version 4.0.12

Version 3.5.3 works correctly.

Bugs in select2 version 4.0.x

Bugs occur only in case select is multiple and using option groups (optgroup)

1. selected options are still visible in autocomplete
   • Steps to reproduce:
   1. type Alaska
   2. press enter to select Alaska
   3. type Alaska again - expected: option is not visible, actual: option is still visible
2. removing selected option opens autocomplete
   • Steps to reproduce:
   1. type Alaska
   2. press enter to select Alaska
   3. click to 'x' to remove Alaska - expected: option is removed, actual: option is removed and autocomplete is shown
3. mouse click and keyboard enter behave differently
   • Steps to reproduce:
   1. type Alaska
   2. press enter to select Alaska
   3. type Alaska again (due to bug#1 this option is still available)
   4. press enter (nothing happens)
   5. type Alaska again (due to bug#1 this option is still available)
   6. click mouse to select Alaska - expected: should't be available, actual: removes option from selected options