viewer: check for gstreamer plugins at application launch.
python: check for buffer.data access.
build: explicitely requires zlib.
buffer: change buffer.data type to char *, instead of void *.

untyped pointers seem to be handled incorrectly by language bindings.
It should fix https://bugzilla.gnome.org/show_bug.cgi?id=706531.
python: add a link to the hexadecimal dump blog post.
build: make configure work even without GOBJECT_INTROSPECTION_CHECK.
build: remove GOBJECT_INTROSPECTION_CHECK leftover.
viewer: warning fix after buffer->data type change.
gv_stream: use the right format for gint64 values in debug messages.
tests: a small get_time test.
camera: fix a clang scan-build warning.
camera: fix a possible NULL dereference crash.

It would happen if either minimum or maximum placeholder is NULL, and
using a The Imagning Source camera.
tests: compilation warning fix.
gvsp: set a correct payload type in data leader.
viewer: remove useless file.
gv_interface: correctly use g_hash_table_replace.

g_hash_table_insert removes the old value but not the old key, which is
wrong in this case, as the key is stored in the value.
fake_gv_camera: listen for discovery packets on 255.255.255.255 address.
Updated Russian translation