Replaced "NodeModel.OldValue" with "NodelModel.CachedValue"
Updated all relevant test cases to use "NodeModel.CachedValue"
Merge branch 'master' into PainKiller

Conflicts:
	src/DynamoCore/Models/NodeModel.cs
	src/DynamoRevit/VisualizationManager/VisualizationManagerRevit.cs
Migrate SunPath Direction
Refactor function initializer into the functiontable class
append the curveElement.curve node
Add type conversion to migration
Merge pull request #1579 from junmendoza/GlobalFuncTable_Initialize

Refactor function initializer into the functiontable class
Merge pull request #1580 from Zhengzi/Migration

append the curveElement.curve node
Merge pull request #1578 from ellensi/master

Migration
append element.geometry node to it
Merge pull request #1575 from Benglin/PainKiller

Optimized the way NodeModel handles its MirrorData
Migrate BestFitPlane and BestFitLine
Merge pull request #1581 from Zhengzi/Migration

append element.geometry node to it
Build fix: NodeModel.OldValue was renamed to CachedValue
Merge pull request #1584 from Benglin/master

Build fix: NodeModel.OldValue was renamed to CachedValue
Fixed test cases which were using old verification mechanism.

1. Added Dummy Node check for all three tests.
2. Turned on one test case which was marked as inconclusive and added verification to that.
3. Currently all these tests are failing, two of them because of valid reason and one of them because of TestFramework issue. I will talk to Ian and get it fix. Even that one test failing make sense to merge because at least this will check dummy node.
Fix Bug http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-3234
Fix changeSetCompute on deleting code in a CBN with a function definition

1. Fix delta compute when code was deleted in a CBN but the function
definition did not change.
2. Testcases
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into GlobalFuncTable_Initialize