Because of Sparkle, it's now required to build dupeguru on 10.10+, but with MACOSX_DEPLOYMENT_TARGET, which we now properly set, the results properly runs on 10.8.
This requires a python that has also been compiled with MACOSX_DEPLOYMENT_TARGET=10.8
Following the refactoring that has been initiated in pdfmasher's
"vala" branch, I pushed more progress window logic into the
core.
The UI code is now a bit dumber than it used to be, and the core
now directly decides when the progress window is shown and
hidden. The "job finished" notification is also directly sent by the
core. Job description update logic is handled by a core gui
textfield.
Job description contsants also moved to the core, triggering
a localisation migration from "ui" to "core".
