Feature request - allow dot repositioning

[vkbellis]

I understand that dots can be deleted, but they sometimes only need to be moved. Please consider adding that ability to DotDotGoose. One possible method would be to single left click to select a dot, then holding the Alt key drag it to a new location.

[persts]

@vkbellis A move feature was also requested in #27 . It has already been a planned feature for DDG v2, but I don't know if we will ever be able to make v2 happen. Now that there have been multiple requests for a move feature, I will see if we can find some time to add it.