deleting
moved funcHistory struct to main

Deleting a now empty file
git.go files for execing and parsing file revisions

git.go has functions to parse and make a git log,
scan a revision of a file and to extract a changed function
signature between revisions
mustScan functions and other minor helpers

utilities.go has functions that panic if a file
fails to be read with scanner.Scan() (and it returns
these scanned files as a slice of strings).

It also has a function to determine a file extension as well
as to determine if two functions differ between git revisions
refactored, gitHistWalk is main function

main now has mostly just a function to walk between revisions
of a file and parse the changed function
refactor funcBounds

funcBounds now returns the bounded function as a slice.
Also extract func works better, but is still globby (see TODO)