subpart label and hover

git-svn-id: http://fritzing.googlecode.com/svn/trunk@6956 85f94c43-f63a-0410-9d22-21439860c375
split parts save and load

git-svn-id: http://fritzing.googlecode.com/svn/trunk@6957 85f94c43-f63a-0410-9d22-21439860c375