Make the usage-printout more beautiful

usage: programname [options]
options:
        -compile        [compile-options] compiliation of a file
        -eval <file>    [eval-options] interprets a file
        -repl   starts the interactive interpreter
compile-options:
        -i <file>       input file
        -o <file>       output binary-file (can be left out)
        -s <file>       output assembler-file (can be left out)
eval-options:
        -heapsize <size>        size of the heap in bytes
        -gfx            enable the graphic module