Fixed some small issues in webservice.c

1) download_dialog_status_text() had some statements with no effect
due to missing return keywords. This fixes incorrect error reporting.

2) Optimize the traversion of the response XML. Assuming that the
status tag should be always under the root tag. We check if the
root tag has children and enter a loop until we find a the
"download" or "error" node names. If there are no children
we return a parser error.

3) Clamp the number of input characters to 30 in the user id
GtkEntry field.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add libsoup to Windows installer

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix potential crash with old XML files

A file with no divecomputer section in a dive can trigger a SEGV as cur_dc
could be NULL.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>