Fixed compiler warnings (squirts team with spray bottle)

This isn't coooool

```
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNetlist.java:31:21: warning: Name 'in_to_out' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNetlist.java:46:21: warning: Name 'in_to_out' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNetlist.java:58:9: warning: Name 'n_in_to_out' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNetlist.java:69:21: warning: Name 'in_to_out' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNetlist.java:78:9: warning: Name 'n_in' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNetlist.java:80:9: warning: Name 'n_out' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:43:23: warning: Name 'in0_to_out0' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:47:15: warning: Name 'netlist_case0' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:48:16: warning: Name 'case0_data' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:65:23: warning: Name 'in0_to_out0' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:68:23: warning: Name 'in1_to_out0' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:72:15: warning: Name 'netlist_case1' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestNoMultipleDriversCheck.java:73:16: warning: Name 'case1_data' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/back/TestVHDLCodeGenerator.java:60:21: warning: Name 'in0_to_out0' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/serialization/TestSerialization.java:116:18: warning: Name 'IN_NODE_NAME' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/serialization/TestSerialization.java:117:18: warning: Name 'OUT_NODE_NAME' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/serialization/TestSerialization.java:118:18: warning: Name 'DIGITAL_IN_PORT_NAME' must match pattern '^[a-z][a-zA-Z0-9]*$'.
[ant:checkstyle] /Users/lucaswoj/Projects/Manifold/Repository/src/test/java/org/manifold/compiler/serialization/TestSerialization.java:119:18: warning: Name 'DIGITAL_OUT_PORT_NAME' must match pattern '^[a-z][a-zA-Z0-9]*$'.
```