Update mesh_tools.py

[kujaku11]

Added a function for rounding a number. This will eliminate 0's when the mesh elements are single digits as described in issue #157 .

Added a function called get_rounding that will round to the correct significant digits. Previously it was set to -2, which causes 0's when the mesh elements are 0.

Description

Added the get_rounding method to all the mesh creating functions to make sure the rounding is properly set.

Motivation and Context

fixes issue #157

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.