Remove start and end parameters from find_iio_names

I have no idea what they are supposed to do and we don't seem to be using them.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Add filter parameter to find_iio_names

This allows us to filter the devices by type, e.g. to just get triggers.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Add a trailing newline when writing attributes

This allows us to write an empty string to attributes.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Add trigger dialog

The trigger dialog allows to select the trigger for the device and to configure
the triggers frequency.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Move the horizontal scale label next to the toolbar

Instead of putting it in the toolbar move the label to the right side of the
toolbar. Otherwise it will impact the size of the other toolbar buttons.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Use a GBinding to bind the stock-id of the capture button to its state

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>