Create ~/.ssh/ if missing
Add config for SSH on https port at ssh.github.com

https://help.github.com/articles/using-ssh-over-the-https-port
Add special case for ssh.github.com to connect to port 443 (https port)
instead of SSH standard port.
Add aliases *.ssh.github.com that connect to port 443.
Fixes issue #12.
Update links to Github help pages
Add support for '@github' suffix for users on the command line

The suffix is still optional.
This is a first step to add support for other targets than Github.
Bump $VERSION to 1.011
README: changelog for release 1.011
Move config rules for ssh.github.com above *.github.com

ssh_config parsing rules keep only the first value set to an option. Our
rule order was broken for hosts gist.github.com and ssh.github.com (and
their *.gist.github.com and *.ssh.github.com aliases).
Really fixes #12.
Fix update of known_hosts_github file

The size check had to be updated for the update to be triggered.

Also, the known_host entry for ssh.github.com is now specific to port
443: ssh checks this entry first (before a more generic
"ssh.github.com" entry), so this *may* speed-up connection.
Add *.443.github.com as aliases to *.ssh.github.com
Minor optimization: group multiple 'use constant'
Fixes #13: default github account was lost

When we run again github-keygen after a default account has been
previously selected (--default) the default was not preserved.
https://github.com/dolmen/github-keygen/issues/13

That was broken by 7f3054e5 (released in v1.004).
Optimizations in config parsing
README: changelog for fixed issue #13
Release v1.011