Although traders are still nervous about possible fallout from the Greek situation, the greater potential for commodity market impact comes from China where the government is struggling so far unsuccessfully to halt the Chinese stock market implosion. General Comments Overnight and today, corn, wheat and soybean futures all traded up and down on both sides of Tuesday's closes in noticeably lower volume than during recent sessions. Corn and soybeans managed to close slightly higher, but all three wheat futures markets closed lower. Funds were net buyers of corn, soybeans and Chicago wheat in what appeared to be an effort to defend their recently established long positions. They were successful in corn and soybeans in that those markets did...