Zero-pad screenshot filenames

[utdrmac]

Screenshot option of decktape outputs filenames as such:

$prefix_1_908x681.png
...
$prefix_10_908x681.png
$prefix_11_908x681.png
...

When you batch open the images, they open out of order due to lack of zero-padding in the slide numbers. The above sequence would actually open as 10,11,12,..,19,1,21,22,...

Renaming to 01, 02, 03,...,10,11, etc allows proper ordering when opening files.

Since the total number of slides is known before exporting, it should be easy enough to calculate how many zero's are needed to pad.

[ysb33r]

Probably would be better if the padding can be specified with a formatting string in a similar way that deck2pdf does i.e. %02