[Bf-funboard] Split UV, Individual pivot type & Bounds constrain

[Julio Iglesias]

> http://markmail.org/message/5jv2qpq7bulxyxpx

Thanks! I owe you a beer! :)
Btw, it doesn't work when you drag ("release confirms" on) a triangle
instead of pressing "G". But that is not much of an issue.

>> It would be also useful to have kind of an "island bound" constrain,
>> where user could input a value and forget to care about the space
>> between islands (including image bounds) for the rest of the uv
>> editing.
>> Meaning: we activate it and enter 4px as value, then whatever we do,
>> we won't cross any island and all will have a separation of 4px.

> Not sire about this one, depends on how the constraints are kept, but
> I never found keeping UVs in the area I wanted them to be an issue
> needing a feature like this.

When you work with low res stuff and you have a lot of islands, you
gotta be careful even with a single pixel.
But now that I think, maybe what I suggested was too complex. Maybe
just a simple visual aid would help here:

https://dl.dropbox.com/u/2294713/uvaid.png

In case it isn't clear: User inputs a value for an invisible Island
border, when a border interesects another, the result is displayed.

Also "edge overlay" could be useful, to make more clear when an edge
is on top of another, or more than one island taking the same space.