Ptm-pose

Major updates

- PTM coordinates dataframe updated with additional PTM information regarding the degree of evidence, such as whether it has been observed to be lost/gained across isoforms, how many studies the PTM has been observed in, number of different databases, etc. In addition, functions to filter PTMs by this additional information to focus on PTMs with the strongest evidence has been implemented
- Package has been updated such that it comes pre-installed with annotations in a .gmt file format to allow for quick addition to new datasets. Other functions have been reworked to fit this format.
- New downstream analysis functions for things like KSEA, Kinase-Library motif analysis, and improved PTM annotation enrichment
- New module for integration with NEASE, particularly for comparing protein interactions identified by the two approaches

The first official release for PTM-POSE, which includes:
1. Base functions for identify PTMs differentially included due to splice events
2. Base functions for identifying PTMs with altered flanking sequences, as well as some basic analysis functions on the flanking sequences
3. Functions for annotating the above outputs with functional information
4. Functions for easily accessing functional information of spliced PTMs

Future versions will maintain this basic structure, but expand on available analysis and plotting tools