Player defined Ship names.

# What is it?
As requested in the "[Player defined Ship names](http://pioneerspacesim.net/forum/viewtopic.php?f=3&t=247)" thread.

This add a `m_shipName` to the `Ship` class along with loading & saving. There's a hacky new text edit box in the ship info screen too.

# What's missing?
There is no generation of ship names as of yet.
I figure either someone can help me come up with list of suitable words for the name generation or we can just add it in another PR.

Andy