API version 5: changes and discussion

[haste]

Current changes:
- The license has been changed to MIT, from ARR.
- oUF:UpdateElement(name) has been removed. This function has been replaced with element:ForceUpdate().
- element:Update() has been renamed element:Override() to correctly reflect what it actually does.
- Elements no longer require element:GetParent() to return the oUF object. Elements now have a element.__owner which points towards self at enable.
- Support for cataclysm has been added.
- HealPredition element added.
- HolyPower element added.
- PhasingIcon element added.
- SoulShards element added.
- QuestIcon element added.
- EclipseBar element added.
- ReadyCheck element added.
- oUF automatic frame name generator has been improved. It will no longer generate names such as: oUF_LilyPartyParty.
- Elements no longer use the .Override function directly with the event system.
- Support for blank parent frames on headers.
- Added a third argument to the style function indicating if the frame was spawned from a header or not (isSingle).
- Minor optimizations of common tag paths.
- [defict:name] has been renamed [deficit:name].
- Added ['pereclipse'] tag.
- tagfs.overrideUnit has been added. It basically tells the tag system that it should feed the "real" unit to the tag function as a second argument.
- self.disallowVehicleSwap has been removed. Vehicle switching is now always enabled.
- Sub-objects now correctly have self.id set.

Known issues:
- Headers: Due to how RegisterAttributeDrive works on 4.0.x, clicking _can_ go void on frames. The solution to this is to use self:RegisterForClicks('AnyDown') instead of AnyUp. Another solution is to NOT use the visibility field in :SpawnHeader().
- Portraits: On header frames this will constantly reset their animation due to the bug mentioned above

Needs testing:
- All of the new elements require as much testing and input as possible.

Updating version 4 layouts to version 5:
- Any use of oUF:UpdateElements(name) needs to be changed to element:ForceUpdate().
- Any use of element.Update needs to be renamed element.Override.
- If you are checking for an automatically generated name in your style, then you might have to update this check.
- All usage of restricted functions on secure frames (self:Set{Width,Height,Size,Attribute} and a ton other) need to be split into two parts, one of headers and one of single spawns.

-- single units can be done within the style function:
local style = function(self, unit. isSingle)
-- 8<8<8<8<8<8<8<8<8<8<8<
    if(isSingle) then
        self:SetSize(width, height)
    end
-- >8>8>8>8>8>8>8>8>8>8>8
end

-- header units are slightly more annoying:
local party = self:SpawnHeader(
    nil, nil, 'party', 'showParty', true,
    'oUF-initialConfigFunction', [[
        -- unit can be nil here, and usually it will be: {raid,party}{,pet,target}
        local unit = ...
        -- Do note that this is an string, and you can't actually use locals like this:
        self:SetWidth(width)
        self:SetHeight(height)
    ]]
)

-- If you need local variables within oUF-initialConfigFunction, you can do:
    'oUF-initialConfigFunction', ([[
        -- unit can be nil here, and usually it will be: {raid,party}{,pet,target}
        local unit = ...
        -- Do note that this is an string, and you can't actually use locals like this:
        self:SetWidth(%d)
        self:SetHeight(%d)
    ]]):format(width, height)