Use more convinient inheritance trick.
Change indentation: 4 spaces -> 2 spaces.

2 spaces is a common indtentation in JS world.
Restore 4-spaces indentation since it's the best!
Reorganize repo again.

I hope it's a final reorganization. :(
Minor improvements in README.
Added `use strict` to listbox.js
Tests.js is splited into two files.
More prettify example.
Some code improvements.
Added some meta-information.
Fixed testsuite for Firefox.
Merge branch 'devel'. Version 0.2.0.