With this patch, the libimagentrylink library interface gets renamed.
The trait gets renamed to the more descriptive name "Linkable", the
functions get renamed to not contain any notion of "internal" anymore.
This patch also adapts the whole source tree for the new libimagentrylink
interface, also renaming variables to not contain "_internal_" anymore.
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
