Feature/improve code readability

These commits are purely costmetic changes to improve (IMHO) code readability.

The command-pattern architecture used in the GUI part of the simulator causes a number of one-shot objects to be created; these need not be assigned to a variable, but can be used in a single statement (calling `execute()` on the object returned by the constructor).

Other changes include stripping of trailing whitespace and superfluous empty lines and using extended `for`-loops when the loop index is not used or needed.

I have tested this quickly on Ubuntu 13.04 64bit with a current JDK/JRE. I recommend testing it on other platforms as well, just to make sure none of the changes actually break anything (they're *supposed* to be cosmetic, but I might have messed something up, you never know).