fix add_contact and rename_contact

Fix when crashing if print_name is null

Fix it to work on current stable gentoo.

Fixed random crashes and crash on group link request

- (Random crashes) Fixed uninitialized variable prompt_was; please, use static variables to make life easier to everyone.
- Removed duplicate line 2138. The print_start/print_end mechanism is weak, there's a lot of redundant code and bugs are hard to catch.

Unnecessary brew installs

do fflush instead of readline when readline is disabled.

Updates Fedora install guide

Replaces `yum` with `dnf`.

 - fixes issue when output is getting buffered and is not sent until message is received or program has stopped
 - I used this answer http://stackoverflow.com/a/1716621/74167 for solution

Brew can do it inline.

Enabled Peer.fwd_msg for python scripts

Use sizeof() to get size of sun_path.

Add get_self command

 - Size varies on platforms, OSX has 104, Linux has 108.