Fix issue where keyboard sometimes ignores first keyboard tap

Under some conditions the keyboard does not process its first touch event properly. This causes characters to be mistyped or not typed at all. This pull request fixes the issue by tapping the keyboard twice in the bottom left corner before actual typing begins.

I suppose a less invasive fix might be possible, but I failed to come up with one that worked, and this one is at least simple and harmless.

The typing test suite passes with this change.