gitignore .pyc; make vistory.py more robust to lack of node children


+ .gitignore *.pyc
+ .gitignore egg dir
+ robust to empty node lists and nodes without children

# To reproduce ERROR:

    $ cd ~/src
    $ git clone https://github.com/ggp-org/ggp-base.git
    $ ~/src/ggp-base/src/org/ggp/base/util/gdl
    $ j2py GdlUtils.java GdlUtils.py

# ERROR Traceback:

Traceback (most recent call last):
  File "/home/hobs/.virtualenvs/ggpy/bin/j2py", line 259, in <module>
    sys.exit(runMain(configScript(sys.argv[1:])))
  File "/home/hobs/.virtualenvs/ggpy/bin/j2py", line 57, in runMain
    return runOneOrMany(options)
  File "/home/hobs/.virtualenvs/ggpy/bin/j2py", line 83, in runOneOrMany
    return runTransform(options)
  File "/home/hobs/.virtualenvs/ggpy/bin/j2py", line 135, in runTransform
    module.walk(tree)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 86, in walk
    visitor.walk(child, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 86, in walk
    visitor.walk(child, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 86, in walk
    visitor.walk(child, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 86, in walk
    visitor.walk(child, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 86, in walk
    visitor.walk(child, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 83, in walk
    visitor = self.accept(tree, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 43, in accept
    return call(node, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 484, in acceptIf
    nextBlock.walk(nextNode.children[1], memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 86, in walk
    visitor.walk(child, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 83, in walk
    visitor = self.accept(tree, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 43, in accept
    return call(node, memo)
  File "/home/hobs/.virtualenvs/ggpy/lib/python2.7/site-packages/java2python/compiler/visitor.py", line 443, in acceptFor
    if not node.firstChildOfType(tokens.BLOCK_SCOPE).children:
AttributeError: 'NoneType' object has no attribute 'children'