Merge pull request #64 from macgitver/feature/ReferenceView

Feature: reference view context menu
Don't use Git::Repo in HistoryView
Remove unused and deprecated MacGitver::repository
Remove submodule module (softly as discussed)
Remove unused variable including it's compiler warning :-)
Move IndexWidget away from MacGitver::repository()
Remove remaining deprecated usage of repo switching
Remove some QList in favor of QVector
use compare method instead equal operator to find "similar" refs