Added recent jqcloud, symlinked it and added it to footer

git-svn-id: https://develop.sub.uni-goettingen.de/repos/ent/archaeo18/branches/ROPEN@838 aa2a3981-a392-0410-b963-7749bab6effd
Lowered number of tags to be shown in tag cloud from 50 to 20

git-svn-id: https://develop.sub.uni-goettingen.de/repos/ent/archaeo18/branches/ROPEN@839 aa2a3981-a392-0410-b963-7749bab6effd
Bugfixes in CSS. Added referenced image file

git-svn-id: https://develop.sub.uni-goettingen.de/repos/ent/archaeo18/branches/ROPEN@840 aa2a3981-a392-0410-b963-7749bab6effd