disable buttons while downloading

Simple patch to enable/disable extra buttons while downloading.
The UI should be blocked during the download.

Signed-off-by: Danilo Cesar Lemes de Paula <danilo.eu@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
set the download progress bar to zero after a download

Before that, the behaviour was that in case of an error or a
re-download, the progress bar would appear for a few milliseconds with
the old value.

Signed-off-by: Danilo Cesar Lemes de Paula <danilo.eu@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
reseting progress_bar_text for new downloads

if the user tries to redownload something from its dive computer
the interface will be stuck since progress_bar_text won't be empty in
the second run.

Even if I don't really like this idea of that value being changed by
downloadfromdivecomputer.cpp and libdivecomputer.c, that value needs to
be reset by someone.

Signed-off-by: Danilo Cesar Lemes de Paula <danilo.eu@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>