setting up gitignore after migration from svn to git
also add mccoy key to gitignore
since there is no increasing commit id as in svn anymore, use a 'revision' modifier.
also bump version to 2.2.0 in preparation for the next release.
Merge branch 'feature-git-migration' into next

basic setup for git migration
move license file to LICENSE.md
Adding short README.md, extend later.
Updating all homepage references to our new home at github.
fix copyright year
updating copyright year
updating copyright year
fixing thunderbird 24 compatibility, which uses a different kind of enumeration/iterator
Merge branch 'feature-thunderbird24-compatibility' into next
Merge branch 'feature-github-preparations' into next
updated logo
Merge branch 'feature-new-logo' into next
fix line endings
change version compatibility in install.rdf
Merge branch 'feature-cleanup' into next
Merge branch 'next'
Fixing Thunderbird 24 compatibility
Switching to new homepage at http://threadvis.github.io