Math error (random generation of zero) causing map gen to fail

There is a math error in MapGenBase.java (MCP Name) in the generate function.

When the per chunk seeds are being generated there is a very small chance that either the x or z can be equal to 0.

When doing the per chunk math it multiplies by 0 causing every chunk in the axis to be the same.

The following seeds are affected:

107038380838084
164311266871034

There needs to be a check so that if those values are 0, then it should be set to 1.

I have recorded a video demonstrating this, including a fix:
https://www.youtube.com/watch?v=D5c-DZA2R2U&feature=youtu.be