Program enhancements

[r41d]

• feat(dtnecho.py): add possibility to use custom port names
• feat(dtntrigger): add simple print functionality
• feat(dtnsend): add option to pass message directly as paramter

[gh0st42]

Thank you for the PR, some nice finds but some things are still unclear.
Mainly the use of chrono and the send message parameter I do not see why it would be needed.

[gh0st42]

what's the problem with "echo test | dtnsend" ? why introduce more code to do the same? I do not see a use case, pleasure explain

[r41d]

I found it to be more tedious to use pipes rather than having the command, especially when using dtnsend in contexts where it's not just called from the command line but, for example, in a script of invoked from other places. So essentially the reason is that I found it much more comfortable to work with and I don't think it's too much code. But if you absolutely object it I would remove it.

[gh0st42]

i think i would keep it in line with other unix tools such as netcat that also just use pipes, less code duplication and following the unix philosophy