[WIP] Test Suit for Editing Functionality

I need to critically review editing functionality and write automated tests.

- [ ] `mergeTranscripts` and `resizeExon` and `normalizeFeature` each has the same code to "compress" the gene model.
    - [ ] extracted it out into a separate function & write unit tests for the same.
    - [ ] write unit tests for merge, resize, and normalize (normalize may be difficult and can skip for later)