renderparameters are becoming central all of alignment, reflect this in
its javadoc
renamed res to meshCellSize and made it a double
added getMaxX and getMaxY to TileSpec
export and default set doFilter parameter correctly
replaced `messy' merge methods by generic implementation that covers both
objects and primitive types through autoboxing

TODO Think about how `unset' parameters shoud be handled.  Currently,
JCommander fills them with system defaults which makes them available
as correct values later.  applyBaseParameters would prefer to understand
them as unset.  But why should applyBaseParameters only override unset
values?  What about applying loaded parameters first (all of them) and
then parsing the rest of the command line?  Or initialize otherwise...
not sure yet.