Webservice: Full functionality

[wrznr]

• POST requests
• JSON results
• gp mode
• hy mode
• JSON in
• no error 500 @haoess

[wrznr]

JSON notes:

• fmt: in and out format
• ifmt: in format
• ofmt: out format
• we want POST/PUT (due to length restrictions in GET/URL)
  • content type has to be specified
  • named parameters
• precedence for GET over POST parameters