igvR_Function.R - some suggestions

[paul-shannon]

@mariam16548

• the bam and peaks files are not in the repo, so I can't run the test
• you check file.exists(FileBam) AFTER you call igvBam. should come before
• please use camelCase capitalization everywhere

If the 3 files (bam + 2 peak files) are small enough, please put them on the repo. Then I look forward to running the demo.