write primitive functions to DOT file
write tuples and variables to graph
write expression edge labels to dot file
version bump 0.2.1
use manifold-core v0.8.0
sanitize namespace identifiers (fixes #35)

Conflicts:
	src/test/java/org/manifold/compiler/front/TestNamespaceIdentifier.java
version bump v0.2.1
refactor: abstract method writeToDOTFile()
Merge pull request #34 from mtrberzi/expression-graph-visualization

Expression graph visualization
Merge branch 'master' into issue35
remove docblock comment
more descriptive error message
Merge pull request #36 from mtrberzi/issue35

Sanitize namespace identifiers
Merge branch 'master' into expression-rework

Conflicts:
	src/main/java/org/manifold/compiler/front/NamespaceIdentifier.java
remove duplicate visit() method
remove unnecessary compilation dependency
removed todo; opened #38
remove leftover debugging code
remove todo; opened #39
remove unnecessary todo