added some more tests

git-svn-id: https://svn.code.sf.net/p/cocotools/code/trunk@2800 f53af814-44c1-4224-a865-87766a68302d
fixed empty spec bug

git-svn-id: https://svn.code.sf.net/p/cocotools/code/trunk@2801 f53af814-44c1-4224-a865-87766a68302d
added function coco_explain_settings

git-svn-id: https://svn.code.sf.net/p/cocotools/code/trunk@2802 f53af814-44c1-4224-a865-87766a68302d
added [OPTS] token for readability of grammar

git-svn-id: https://svn.code.sf.net/p/cocotools/code/trunk@2803 f53af814-44c1-4224-a865-87766a68302d