add test case for migration class
fix bugs
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
fix the bug at the string concat
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
change the math.average
Merge branch 'CrossFade' of https://github.com/Benglin/Dynamo into CrossFade
fix the bug in slice list node
change some test cases' parameters
Merge pull request #30 from Zhengzi/CrossFade

Merging this now with the understanding that the comment will be addressed immediately after this.