Expand and collapse folders recursively

Directories may be expanded or collapse recursively by holding `alt` when using
the keyboard or mouse. Incorporates pull request #88. Addresses issues #19 and
Clarify recursive expand/collapse command names
Consolidate recursive expand/collapse into existing methods
Add alt+click tests for recursive expand/collapse.

* Add tests for alt+click to recursively expand or collapse directories
* Rename keyboard related tests
Merge pull request #163 from adurity/recursive-expand-collapse

Expand and collapse folders recursively