Update _touch.py
Update _touch.py

Add keyword 'click a point' to click on a specific point using given opt(x,y)
Raise exception error if appium can't perform click on that point.
serhatbolsu/robotframework-appiumlibrary,jollychang/robotframework-appiumlibrary,yahman72/robotframework-appiumlibrary,Meallia/robotframework-appiumlibrary,minhnguyenphuonghoang/robotframework-appiumlibrary