Add IntelliJ Project
Set project JDK and source encoding
Use Deque, ArrayDeque, and IntegerStack as appropriate instead of the obsolete Stack class
Merge pull request #10 from sharwell/stacks

Use Deque, ArrayDeque, and IntegerStack as appropriate
Use Ant for downloading ANTLR and generating grammars during the build
Sign contributors file
Merge pull request #9 from sharwell/intellij-project

IntelliJ project
Fix grammar generation on OSX
Merge pull request #12 from sharwell/ant-fixes

Fix grammar generation on OSX