allow VM names with white space.

I still don't like the idea of white space in names!

The createvm form is now just a name, no os type in the form, the ostype
selection menu before the form should suffice.
vmname with white space now working.

new function to getvmlist, similar to getoslist.
new option for vb_list long listing.
reject blank vm name.
rephrased cancel button and help texts.
tidied up widget titles and button labels.