Update 2 - The Second Pass - IF

- HistoryNode now has a style applied to it.
- HomeButton now has a z-index of 100.
- Start/Close 'home' button now checks if elements exist and deletes
them on close.
- Reorganized evaluate function.
- Fixed a bug where the Start/Close button would become hidden behind
other elements.
- Removed a deprecated, empty tag 'browserContainer' from the body of
the main document.
- Changed the argument name for the eval 'program' in the main switch
from x to ex to match the evaluate function's argument name.