11 - move from ANTLR 2 to ANTLR 3

[joshsh]

It would be nice to move to ANTLR 3.  Unfortunately, the Java
implementation of ANTLR 3 reads its input streams "greedily", putting the
entire stream (until it reaches EOF) into a buffer before it begins
parsing.  This makes the provided character stream classes unusable for an
interactive interpreter like Ripple's, so some custom code will need to be
written to allow ANTLR to read characters as they become available.

Original link: http://code.google.com/p/ripple/issues/detail?id=11