Rename variables in testcases from 'local' to 'loc'

This is to avoid name clash with the 'local' keyword
Syntax support for the local keyword
Update nested lang testcases and add new testcase
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into localkw
Addressed review comments on short circuit condition
Merge pull request #1947 from junmendoza/localkw

Syntax support for local keyword