Enhancements: NMM Examples, PTE Significance Testing, and More Sanity Checks

[patrk]

• NMM Examples: include examples using Neural Mass Models to show how PTE can reproduce connectivity.

• Significance Testing for PTE: make PTE results more reliable, implement significance testing. this will help users know if the connectivity patterns they see are statistically meaningful.

• Expanded Sanity Testing: add more sanity tests to make sure new updates don't break anything. Use simple synthetic data with know expected results, kuramoto models, NMMs and / or open source brain connectivity data