Add visible timestamp to the photos and videos

[strlcat]

I always missed this feature in android builtin camera app. Both photos and videos should be supported.

It could be also very good to customize additionally:

• Timestamp font selection,
• Size and placement,
• strftime(3) format specification (including arbitrary short strings ignored by strftime)

It is possible to implement this within android framework? (Idk personally, I am C programmer)