Speed up gsp locations

[peterdudfield]

Pull Request

Description

Speed up gsp locations by

• checking to see if no nans,
• if no nans get gsp locations in one go

Fixes #304

How Has This Been Tested?

• unittest tests,

• tested for speed up, for 10 gsps, ~0.13 seconds to --> ~0.01 seconds ===== X10 speed up

• No

• Yes

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked my code and corrected any misspellings

[JackKelly]

Love this! A really elegant solution! And a 10x speedup is fantastic!

Two tiny comments...