Add some features

    1. Add *.swp to .gitignore.
    2. Add file dump.h for debug.
    3. Fix a bug that lua stack will remain a object after calling get_length function in LuaHelpers.h.
    4. Complete Iterator.h. Now we can use Iterator to iterate a table.
Merge pull request #53 from sKabYY/skabyy

Add some features