Improve the way messages are sent

We want the proper encoding and content-type to be set when sending the
mail, but human-readable plain-text for composing. So split the code in
two parts: the presentation and the transport conversion.

Signed-off-by: Felipe Contreras <[email protected]>

Improve build instructions

Signed-off-by: Felipe Contreras <[email protected]>

Delete last line in 'show' view

It's a bit annoying.

Signed-off-by: Felipe Contreras <[email protected]>

Simplify VIM::*::current accesses

Signed-off-by: Felipe Contreras <[email protected]>

Counting the number of threads takes too much time

Signed-off-by: Felipe Contreras <[email protected]>

Add basic syntax stuff

Signed-off-by: Felipe Contreras <[email protected]>