caching width and height
separate method that adding resize event and use window.resize instead of setInterval
merge master
fixed jshint error
renmove unused if statement
unify the variables name
Merge pull request #97 from takashi/fix/rewrite-resize-handling-method

Fix/rewrite resize handling method
Merge pull request #98 from takashi/fix/unify-variables-name

unify the variables name