natashabatalha/PandExo: Pandeia/PandExo v1.3 Release

Moving forward Pandexo releases will coincide with Pandeia releases.

• This new release includes major updates to background noise calculations. There are now two options for background noise (see Adjust Background Level in the tutorials).

• Users can either set zodimin or ecliptic as the location, and then set low, medium, or high based on what they expect. This is particularly important for MIRI LRS when looking at smaller planets. Calculations can expect to differ from 10-40 ppm if planet is in ecliptic at a high background level.

• Users will have to download the new Pandeia reference data

• Added NIRISS Order 2 tutorial for users who have inquired about how to do that
• Minor adjustments to web development