Improvements related to multidimNcFiles

[ChrisJohnNOAA]

Description

Actually use the removeMVRows dataset parameter now (which allows turning off the related logic). This can provide a significant performance increase.

Also refactor the general processing while loading files including performance improvements.

Fixes #152

Type of change

Please delete options that are not relevant.

• [ X ] Bug fix (non-breaking change which fixes an issue)
• [ X ] New feature (non-breaking change which adds functionality)
• [ X ] This change requires a documentation update

Checklist before requesting a review

• [ X ] I have performed a self-review of my code
• [ X ] My code follows the style guidelines of this project
• [ X ] I have commented my code, particularly in hard-to-understand areas
• [ X ] I have made corresponding changes to the documentation
• [ X ] My changes generate no new warnings
• [ X ] I have added tests that prove my fix is effective or that my feature works
• [ X ] New and existing unit tests pass locally with my changes