allow urls as command line arguments

to be used by a protocol handler, the command line input should be able to handle urls.

Proposed sheme:

protocol://mode/?param=value1&paramN=valueN

• add procol handler stub d2a05343
• substitute environment variables in file name 98da526e
• generate meaning full error messages in dialog 2432e54c
• add example reg file 585ecb94
• add documentation 04634310