Translate comments, fix code style

This refactoring contains the following changes, all of which are cosmetic
(except removing RoadNodeComparator).

* Fix copyright, 'comparator' spelling
* Remove RoadNodeComparator (unused)
* Move the implementation of RoadNodeComparatorInv's operator function into the
    class declaration (was previously placed outside of it, a few lines below,
    for no apparent reason).
* Turn maxMapSize into #define'd constant:
    maxMapSize is used as an upper limit for the map dimensions (it's the
    maximum side-length of any map), and serves to set the size of an array and
    some loops used for pathfinding.
    Since this value is constant and never changed, turn it into a #define
    constant (renaming it to MAX_MAP_SIZE) to allow for better compiler
    optimization.
* Convert all tabs to spaces
* Fix other code style aspects (curly brace placement, space after keywords,
    formatting of function parameters)
* Translate all German comments into English; add some more comments where none
    were present