FileServer: move >>checkDirectoryLayout into >>start
FileServer: rewrite handling of commandline parameters

All methods in the 'accessing' protocol taking one
parameter are directly turned into a commandline
by adding trailing '--' and removing the ending ':'
This does not require the registration of blocks in
a dictionary any more.
FileServer: add --help commandline option
update API-CHANGES.txt
Merge pull request #466 from mkroehnert/server

Update handling of comandline options; add --help option