fixes #214
Merge pull request #218 from yushijinhun/feature-fluid-explosion

Two fluids will explode when they meet.
Merge pull request #220 from way2muchnoise/1.7-update

fixes #214
Add fluids reaction system.

Signed-off-by: yushijinhun <yushijinhun@gmail.com>
chance*

Signed-off-by: yushijinhun <yushijinhun@gmail.com>