Support Storyboard object IDs as keys

Convert . (dot) to _ (underscore). E.g. "label.text" => "label_text"
If first character is number (\d), convert to "n" + "number". E.g. "3fi-xX-nld" => "n3fi-xX-nld"

This makes storyboard object IDs valid static keys
Merge pull request #2 from duemunk/patch-1

Support Storyboard object IDs as keys