Fixes Null marshaling in collection and List tests

- CollectionMarshaler was throwing exception when any item was null
while getting the approx DS type of the items in the collection. Fixed
this by proper null check.
- Removed ArbitraryDimensionArrayImport from IList parameters as by
default IList will be marshaled as arbitrary dimension array.
- ArbitraryDimensionArrayImport attribute is applied to item parameter
of AddItemToFront method, so that a collection can be added to the front
of the list.
- indices parameter of method List.RemoveItemAtIndex is changed to int[]
from object so that only integers are passed. VM will automatically
promote single object to a collection while calling this method.
Before running an expression, clearing its associated warnings
Merge pull request #1292 from ke-yu/fix_spurious_error

Before running an expression, clearing its associated warnings
Merge pull request #1293 from ellensi/ChocoButter-2Become1

Various fixes
Merge pull request #1290 from sharadkjaiswal/DataMarshaling

Fixes Null marshaling in collection and List tests
Form.ByLoftingCurveElements
Merge branch 'ChocoButter-2Become1' of https://github.com/DynamoDS/Dynamo into ChocoButter-2Become1
Get search tags for FunctionDescriptor, xml documentation, add to search dictionary
Ensure in Transaction when regenerating BoundingBox
MAGN-2305. Crash on attempting to get input identifier from empty list.
Merge branch 'ChocoButter-2Become1' of github.com:DynamoDS/Dynamo into ChocoButter-2Become1
TransactionManager.DoAssertInIdleThread - parameterize whether transaction manager should make this assertion, Turn off when running DynamoTestFramework
Merge branch 'ChocoButter-2Become1' of https://github.com/DynamoDS/Dynamo into ChocoButter-2Become1
Re-add ReferencePoint tests
bit of cleanup
removed id copying from If node

does not solve issue where both branches are being evaluated
avoid exception for getElement call with null object
Merge branch 'ChocoButter-2Become1' of github.com:DynamoDs/Dynamo into ChocoButter-2Become1
fixed build error
Merge branch 'ChocoButter-2Become1' of github.com:DynamoDs/Dynamo into ChocoButter-2Become1