updated mkv tools to MKVToolNix 6.4.1
Renamed folders to prevent mulitple folders for the same minor version releases
Added new version 6.5.7 from http://dev.mysql.com/downloads/connector/net/6.5.html
Added new version 6.6.6 from http://dev.mysql.com/downloads/connector/net/6.6.html
Added new version 6.7.4 from http://dev.mysql.com/downloads/connector/net/6.7.html