Merge pull request #1 from a0x77n/master

Test cases for control flow graph.
New utility traversals 'getAllCalls' and 'getNodesWithType'.
Introduced step 'sinks' as a counterpart to 'sources'.
New utility functions for lookup. Removed duplicate definition of 'match'.
Included 'chunks' method in JoernSteps that allows a large set of start node ids to be decomposed into chunks.
Utility traversal numChildren added to ast.groovy.
Added sphinx docs.
More information for the "Getting Started Guide".
Documentation on chunking.
Some additional steps. Split up tests because we're starting to have more than just a few.
Introducing some more tests for data flow before I start to touch the argument-tainting code.
Test for tainted arguments.
Added step to track variables defined in an AST as opposed to the surrounding statement only.
callToCallee.
Utility steps for parameters.
Fix for astNodes.
Added matchParents step.
Added callToAssigns.
Remove outdated "warning" from README.
Added utility step to retrieve functions based on parameters.