Multiple accounts

[Kevin Kévin]

Hi,

Thanks for this excellent interface, now opening multiple mailboxes now requires
less than 30mb of memory on my computer (before it was 10 times more)

To open multiple mailboxes I'm using the command `vmail -c vmailrc` but when
opening 2 or more accounts at the same time, vim complains about using the same
file buffer (vmailbuffer).

As a workaround I've changed lib/vmail.rb:87 to be able to use a specific buffer
for each of my account.

Would it be interesting if I open a ticket and suggest my mini patch?