Make git-gutter:lighter customization variable.
Use make-local-variable instead of make-variable-buffer-local
Add git-gutter to "change-major-mode-hook"
Add 'git-gutter:lighter' explanation.
Bump up version and update Changes
Don't change window-margin if file has no changes.
Add about update change information
Update version and update Changes
Add hook to window-configuration-change-hook.

Fixed problem that 'git diff' is not shown when switching buffer.
Bump up version and update Changes
Disable git-gutter when file is not existed.

And bump up version and update Changes.
Improve git-gutter:in-git-repository-p and error message
Add test of 'git-gutter'
Bump up version and update Changes
Fix 'git commit -v' problem.